This Monster Gun project was sitting on OfferUp by my girlfriend for a bit. I've I talked to the guy for a bit and ended up picking it up.
Looking it over, it's in pretty decent shape and nearly complete! The backglass is also pretty nice! Guy replaced the bottom and painted it.

I've been looking for my first EM game/project for a bit and I think this is an excellent candidate!
I've always wanted an EM rifle game!
The 4/5 years I've been in this hobby - these used to be easier to find. I haven't seen much so was excited when this popped up.

There's NOT a lot of information out there on these games. Midway didn't make a lot of them. Most people don't like them for the design of the score motor/reels.
I'm going to document my efforts here in hopes of getting some good info out there.

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The biggest issue is the outer target motor. I received it with the motor removed and taken apart in a ziplock bag.
After taking a real good look - it's missing a worm gear that connects the motor shaft to the gear box.
I took some mineral spirits, and a bunch of paper towels and q-tips, and cleaned the crap out of it.
Looks way better!
The motor brushes are also missing. I measured the dimensions of the current one and ordered a hopefully equivalent on eBay ebay.com link: Carbon Brushes For Dremel 90827 Rotary Multi Tool 270 280 370 380 4 7X4 7X8 5mm

Otherwise - the stylus/spring is missing, as well as a spring on the stepper unit. The recoil solenoid looks a little toasty on one side and may be fried.
Steve at PinballResource should have them. I've also asked him about the motor/gear.
The rifle butt is also missing. From my research, a Remington 504 or a Marlin 37 will work. The screws are still there. About $15 on eBay.

Anybody have an extra Midway #532 (28rpm) motor? From my research, the Williams 40-2061 (Haunted House cat motor) is an equivalent.
From what I've seen, it looks like there's some common parts between Williams and Midway games at the time.

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OK found a generic Chinese worm gear on eBay, gonna roll the dice on it - $9 - ebay.com link: 0 5 Modulus Brass Gear 20 60 Tooth Worm 3 to 6 35mm Hole Dia Drive Gearbox

Did this

There are certainly some inconsistencies in the rotor measurements, but I'm willing to give it a whirl.
If I could reassemble this motor and get it to spin, I'd be a very happy man.

On that note, let's keep a total of how much I put into this:

Base game: $400
Worm gear/brushes: $16
Home Depot (runner wood, hardware, rifle chain, mineral spirits, new plug): $27
Harbor Freight (3" polyurethane wheels): $18
Schematic: $22
Total: $483

Found what I'm very sure is the exact same game via Worthpoint - https://www.worthpoint.com/worthopedia/1967-midway-monster-gun-rifle-419012034
The P1 credit button is a dead giveaway.

A few photos I've found have different colors on the base, around the backglass, and the rifle counter top. Mine is currently black on the border and counter top. Somebody recently repainted the rifle base and coin door black which looks good. I thought the artwork was red/grey instead of the normal red/purple but it just looks faded.

It was from 2012/2013 and the troublesome motor was described as missing. I noticed that the wire leads coming out of the motor I have are a different color and don't line up with the colored wire leads I have at the bottom of the game. Very likely the motor I have wasn't the original to this game.

While I remain optimistic my gear worm and brushes will work just perfect, I've generated a backup plan:

ebay.com link: 12V DC Motor High Torque Reduction Worm Reversible Turbo Geared Strong Powerful
ebay.com link: US Ship 10 55V 60A PWM DC Motor Speed Controller CW CCW Reversible Plus Driver

Modern electronics and motor solution for $32.
Retrofit the old housing/gearbox onto the new motor, wire it up with a power supply and some relays and I'm in business.

Called Steve Young today. I've known about him, but as this is my first EM, haven't bought anything from him.
I asked about the motor, he said everything he has is on the site.
I asked about rebuilding it, he said that the RAE brand motor I have "he can't help me with".
He tried doing a shotgun repair for one guy and got nowhere.

The brushes came in today. They fit! I roughly reassembled and it looks decent! Some friction in the shaft. If I have a successful test, I'll disassemble to clean the bearing and relube the shaft.

Waiting on Mike Pacak to ship my schematic to verify motor voltages/wiring. Ordered over two weeks now. With the holidays some delay is understandable, but I found it a bit odd on his site how he says that you should expect two weeks for it to arrive. I'll give him a call tomorrow.

Did my best to clean the old grease out of the gearbox.
I thought the gears were held on with hex set screws, unfortunately they use pins. No thanks.
A bunch of brake cleaner, q-tips and scrubbing got it pretty nice! Difficult to get it out between the teeth. I used a toothpick but it only worked so well.
Going to relube it.
Worst case, maybe I can get a high speed/power motor and still use the gearbox.
I may be able to calculate the gear ratios, worst case there's cheap RPM gauges on eBay ebay.com link: Digital Laser Photo Tachometer Non Contact RPM Tach Meter Motor Speed Gauge USA

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Called RAE motors today. The kind woman was able to look up the part number and see it was for midway mfg. Unfortunately they had no technical specs/drawings/parts. Worth a shot.

Called Mike Pacak and he said he shipped the schematic last Thursday. Can't wait to get it! I have a rifle champ schematic. It's from 3 years before and a similar layout with rotating/alternating targets as well as 3 different timing periods. Despite the proximity in production, looking inside the games seem to vary greatly.

Also remembered that there's some big resistors to drive the outer target motor in different speeds. Mine are missing. Hopefully the schematic will reveal the values. A kind pinside has a working game and has been providing me helpful details.

Had a dream last night I found some NOS inside art of this game in a pile of beer stickers. Maybe I should stop staying up so late obsessing over this...

I bought a stylus - ebay.com link: New Targeting Arm Stylus and Spring Assy For Vintage Shooting Arcade Games
$6.70, not bad!

Was previously looking at flippers.com, they certainly have a nice selection of NOS hardware. But it's pretty expensive. For $6.70 I can whip up a mounting system with extra hardware and my 3D printer and have a perfect solution!

GREAT FRICKIN NEWS
Cleaned up the brass pivoting bushings on the motor housing with brake cleaner
Dried and relubed with SuperLube
Checked for continuity on the brush holders
Reassembled
Wired it up - I was a bit confused by the 4 wires. Apparently this is called an "universal motor". The attached schematic is how I hooked it up.
IT WORKS!!! It was spinning pretty dang fast! There was some initial sparking but that subsided. I'm going to get some fine sandpaper and clean up the commutator shaft (where the brushes make contact).

Looking at the picture, real proud I got this going from the filthy bag of parts I was given!

I bought the digital tachometer - $8.61 from China. Barely $9 and I tell myself I'll use it for something else eventually.
My plan is to record the top speed for reference in case I ever can find a decent replacement.
Once I get the resistor network setup to control the different speeds, I'll be able to calculate that also.
Then, even if I can't find a motor that's close, I can fake it with a modern equivalent controlled by an Arduino.

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Some interesting progression...

This label says that there's THREE resistors that control the outer target motor (the one I'm working on getting working).
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I look under mine and see no resistors, and some new (orange blue green brown) wires that presumably went to the motor.

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Another photo I've found has the correct color codes for the wiring, but TWO ceramic resistors under there.

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Pinging @valleyguy, he provided me with this picture of his which has the outer motor wire colors that match mine (yellow orange red black).
Now I know what wire goes where on the terminal block.
He has some different value resistors - TWO of them.

The other anomaly that his INNER target motor has THREE resistors on it while mine has zero.
Again, the schematic will shed some light on this.
The different resistor values control the different speeds of the outer target motor.
From what I've seen on the only functional video on youtube of this game, is that the inner motor stays the same speed and is either on or off (no reversing).
On the road today, home tomorrow, hoping the schematic is there.

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Looks great! How did you do your stencils? I have a photo with a clear side/front shot I'm planning to vectorize and laser cut.

What paint colors did you use/how do they match the original? How did you do the "speckle" and what color did you use? Is that on factory cabs?

My cab came primed. I can't tell from photos if it's supposed to be a "cream" color similar to Gottlieb EM's of the era or if they're just stained from time and tobacco. Was planning to go semi-gloss either way. Maybe 2PAC if it's feasible.

Very nice! I may just use rattle cans if I'm lazy. Girlfriend has a house (I live in an apartment) and a compressor so may get a HVLP gun and get into that.

Here is my timer disc at what I *believe* is the zero location.

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Schematic and the stylus arrived today!
Like I feared, the resistor values aren't specified. No biggie, I'll get a few and play around with the speeds to see what I like.
Gonna dig into it tonight to try to figure out the logic/theory of operation.

The stylus is very thin. Not sure what manufacturer used it. While I'm sure it'll work, contemplating getting a proper NOS one. I'll likely try this one and see how it works.

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That'd be great! The stylus certainly seems simple. The spring is extremely sensitive! I was thinking of using a screw, but worried the harder metal would scratch and ruin the copper (?) contacts on the wiper board. I figured I'll give this one a shot since I have it and can calibrate down the road.

Looked through the schematics a bit tonight. Got the reset/start sequence down, I think? First time reading EM schematics.
While these EM schematics are relatively simple, there's a lot going on all over the place.
I was excited to get the schematic, but it doesn't make sense to figure it out on paper - I need to see the game and what it's doing, and use the schematics from there.

The game is in my girlfriend's garage in the suburbs. It's on wheels and I'm contemplating bringing it inside so I can get it working over winter, then finish cosmetics in the spring. I already got the green light from her!
Either way, next time I'm over there I'm going to test all the coils to finalize my PBR order. Also going to pull the target assembly to bring home with me for cleaning!

Paul! It will work great! First you want to clean the old grease the best you can with carb or brake cleaner and q-tips. Then regrease! What does your motor shaft look like?

I got my worm gear today - doesn't fit.
I asked Paul above what his gear looks like.
If I get the measurements of the gear - where can I find a gear that would work? eBay? Local motor shop? Who wants to mill one out for me?

The gears are held on with roll pins - my first time encountering these.
Other plan is get the 50 tooth gear here - ebay.com link: 0 5 Modulus Brass Gear 20 60 Tooth Worm 3 to 6 35mm Hole Dia Drive Gearbox
$11 from China
Then get a roll pin punch set - https://www.homedepot.com/p/Roll-Pin-Punch-Set-9-Piece-61135/206515512
$13 from Home Depot
But I also will need to measure where the motor meets the gearbox and make sure the dimensions fit - another very long shot.

Tough call.
I'm so close I want to stick with this motor/gearbox before going Arduino.
I'll dig around and see what I can find about gears...

This past week I won an auction of a similar motor - ebay.com link: Rinco Instrument Co RAE Motor 35392 Lab Mixer Stirrer

Closely inspecting the photos, the motor housing looks very similar (different finish, extended rear area). But the gearbox looks VERY similar! I rolled the dice on $22 that my worm gear is inside waiting for me.

On a similar note, I picked up a 1972 Midway Bullseye wall game (https://pinside.com/pinball/forum/topic/1972-midway-bullseye-wall-game-repair-and-restoration#post-4187658). I got a more close-up look of the score motor and how it works. The one on monster gun is pretty dirty and obviously in need of a cleaning. It doesn't look nearly as bad as everyone says to take it off and clean it so I'll try doing that in the near future.

With the Bullseye, I have a score motor and an extra gear box. The RPM's are 64/16 (4) vs. Monster Gun 50/12 (4.17). So very worst case it would be a decent substitute.

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Despite having received the above stirrer eBay motor for a week, I finally got around to popping it open tonight. Using the RPM meter (which is awesome btw), it started out at around 25 RPM and got up to 32 RPM. The seller said that it behaved that way. Popping it open and finding some very old grease I can see why.

Popping it apart and comparing:
The motor housing is certainly the same - likely a later model, different finish on the housing
The gearbox housing is certainly similar (same mount)
The brushes/mounts are the same (and nicer)
The stator coil looks the same (and much cleaner)
The rotor also looks similar (I'll compare values?)

BEST OF ALL - THE WORM GEAR IS THE CORRECT ONE
Comparing the gear boxes it looked very similar and putting it on confirmed it.
I feel insanely good I got a perfect solution at a very reasonable price!!! I did a lot of research and my efforts were rewarded.
More-so - the other motor will make an excellent donor for spare parts should I need them down the road.

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Spent a few hours tonight dicking around with the motor and trying to get the gear motor lined up. After repeated failures to get the worm gear working consistently - I noticed that the gears inside the gearboxes are the same size, but the tooth angle is ever so slightly off.

Ordered a roll pin punch kit - https://www.amazon.com/gp/product/B003L7HOMG/ref=ox_sc_act_title_2
I'm going to have to pop out ALL the gears on both gear boxes to swap in the right worm gear paired gear.
Sucks, but it'll give me the chance to properly clean and relube everything!
Then going to measure RPM of the sprocket to see if the motor is a good fit - seeking (near) 28 RPM.
Worst case, the old motor still works and I'll be able to swap the worm gear over to it.
Another $12 for another tool I tell myself I'll use again...

In the meantime, I put together the new motor on the gearbox... looks sharp!

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Went through the dirty task of swapping the gears tonight:

Got the roll pin extraction kit - works well! Roll pins are a bit of a pain to deal with, though.
Pulled the un-needed gear
Pulled the needed gear, shaft, and washers
Compared the two - same size! Different tooth profile.
Cleaned everything with a q tips, a wire brush, and finally brake cleaner
Generously re-lubed with SuperLube
Reassembled
Tested! Works perfect!

Tested at 56 RPM - I find this peculiar because the factory one is 28RPM
Next time I'll swap in the motor that came with it (using the eBay mixer motor) and test it

Still though, insanely happy I resolved my gear issue for just $22!
Silly how much time I have into it to have the motor issue just mostly resolved
Still have a long road ahead, but making solid progress!

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Whipped up the 3D printer tonight...

Popped out the old rivets/bakelite plate
Took measurements
Made a duplicate in Sketchup
Printed
Mounted

I need to secure the stylus in the rear so it doesn't go flying.
A small cotter pin will work. If I can't find one I suppose I'll make one.
The stylus spring is conductive - going to take the stylus wire and crimp it to a circular lug connector and let it sit in there.
I'm not sure why this stylus is flat... hopefully it performs well in all the directions the gun moves.
Another thing knocked out!

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Thanks for the kind words!
I was basing my statement off of the Midway stylus on Flippers.com - https://www.flippers.com/catalog/product_info.php/stylus-p-843

I'm guessing the one i have was meant for motion in only one axis (flat, tapered edges on only one axis).
The Midway stylus from flippers.com appears to be circular with tapers all the way around.

Got a rifle butt! Mine was missing. Not the Midway branded one but I'm happy to have one regardless. $18.
Fortunately, mine already had the mounting screws.

ebay.com link: REMINGTON MODEL 512 550 BUTT PLATE

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Pretty sure - https://forums.arcade-museum.com/showthread.php?t=375409

I agree. I'll be looking to replace my current one. I'll call Steve Young to see if he has any for cheaper.
Flippers.com is a bit much

Worst case, I can DIY. Maybe a small carriage bolt? May be difficult to find a brass equivalent. Any downside in steel? As long as it's conductive I can't see what difference it would make. Spring seems generic.

Much thanks to CactusJack! I whipped up a new bracket for the new stylus and it looks great! Going to solder the wire into the end of it to prevent it from shooting out when I get closer to install.

Good news - I bought a house! Moving in the end of March. This project will get a lot cooler then!

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Been real busy with work and life lately, but this game has certainly been in the back of my head. I also picked up a cheap Captain Kidd that's mostly working! I may sell one but love the idea of two side by side in my new basement! Stay tuned...

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Certainly been dreaming about them! Been swamped with work travel and doing upgrades around the house.
Hoping to make a paint booth setup in the next few weeks and start on the cosmetics!

Been meaning to make a scan of the backglass before I seal it. Busted out the HP4600 tonight and got some high resolution scans. May research some touchups also. I have some Createx transparent paint, curious how transparent it is...

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Side artwork vectorized

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Summer is winding down and I'm starting to get back into this.
Got some paint! Working on cutting stencils and making a spray booth the next couple weeks.

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