The bank relay identification strip is missing. It’s hard to give guidance if you don’t know what relay to look at.

Check if the frame step up unit’s subtract coil is firing on game reset. It sounds like the unit isn’t resetting because its going into extra shots right away like it’s staying on 10th frame.

Wow! What a gorgeous looking machine. Looks brand new! Congrats.

I am a novice at EMs, but I own a 1954 Williams Major League pitch & bat and have fixed a few things on it that may be an issue in yours.

Cleaning those reels and steppers is step 1, so that's good.

My issues were some loose wires at the Jones Plug connectors. They are at the very bottom in your 2nd picture. They're about 8 and 6 inches long respectfully in that pic.

Now, MAKE SURE YOU UNPLUG YOUR MACHINE! Power off at the machine will still get you zapped. It did with mine anyway. So unplug it to be safe. Then, remove those plugs and carefully look at all the soldered connections and make sure there are no loose wires, cracked or cold solder joints. I suspect that your problem may be in there.

Also, take some rubbing alcohol on some q-tips and clean all the connectors. After you clean those connectors, do not plug the machine in or power it on. You need to make sure that rubbing alcohol is 100% dry or you'll start smelling electrical burn. So clean those plug connections all up 1st, then start looking at the solder wire joints and connections.

GL and keep us updated.

You have to inspect all the switches in the frame unit step up coil circuit. If you can post a snippet of the circuit would help. Yes videos have been used here also.

per the schematic it looks like the frame control unit is supposed to step up once on reset.

the frame drum unit should not step up tho. Is the frame control unit EOS switch stuck closed or misadjusted? Usually the EOS switch is mounted on the ratchet/gear side of the unit and is operated by the step-up arm ... switch closes when the step-up plunger pulls into the coil, and it needs to open before the wipers are pushed around far enough to touch the next rivet as the wipers are moving (wipers move when the step-up coil loses power).

as a sanity check, if you reset the frame control unit, how many times can you manually step it up? The schem says 12, and reset is position 0.

ideally, the rivets on the stepper contact plates should be clean/shiny. Dunno if it's just the camera angle, but it looks like you have buildup on the rivets which may or may not be a problem. Depends how conductive it is. A scotchbright pad/synthetic steel wool and solvent like isopropyl alcohol will remove the crud.

The maximum rub warning is how the end of stroke switch short blade is to be adjusted.
Manually hold in the frame unit advance coil plunger and adjust the end of stroke switch short blade to just touch the long blade with a minimum of pressure. Once releasing the plunger, the end of stroke switch must open before the gear advances the fingers to position 1.

Try this.
Reset machine. Reset frame unit to zero position from position one. Finger push the end of stroke switch to connect switch. Does the frame reel advance? If it does the frame unit wiper fingers may be shorting the two sets of rivets causing a short. Possibly the wiper with the yellow paint.

In the pic of the 5th & 6th Player Reset Relay, the 3rd switch from the outside (3rd from the left)
appears to be touching the 2nd (middle switch in that set). Adjust that 3rd switch so all 3 switches
in that set has a gap like the other sets of the 3 switches have..

it does look like that, and the video seems to show the blade deflecting almost instantly as the armature moves.

however, if it was stuck closed, the drum unit step-up coil would stick on after the zero switch on the drum unit closed ... which I assume is on frames 2-10?

take a look where the green-red wire on the eos switch is going. Should be an arc of rivets on the contact plate and that'll tell you which wiper finger is involved.

dave's test in post 14 should let you know if the issue is the eos or wiper contact bridging rivets. If neither, you're down to unlikely things like a solder drip bridging rivets on the wiring side of the contact plate or other odd short circuits.

oops.

the switches should not hit the metal rod. They should be lined up under the fiber disc. That insulates the switches from the unit frame (which is sometimes tied to the yellow wire as a way to connect yellow to wiper fingers thru the metal ratchet).

loosen the switch stack and twist it to get the switches centered under the disc, then adjust the switch blades as needed to get the 1/16" max close amount.

Yup, and I couldn't tell the exact color wire of the center switch, but from the video, it seemed
the Drum Unit stepped up when the Relay Bank energized making it appear vibration from the
Relay Bank could have arch those switches./

There it is. That Frame Unit is tied to the Common Yellow.

go for the pin reset next since pins flipped up could make the game state inconsistent.

first step is to determine if it's mechanical or electrical. I dunno if you can spin the reset motor cam with the power off. If you can, do that and make sure the pins latch down.

look at the relays in the big trip bank (first pic, post #3) and see if the corresponding trip relay for a flipped up pin is tripped. If it is, try and manually reset that trip relay with the power on. If it doesn't let you latch the trip relay up, then you've got an electrical issue always powering the trip coil. Usual problem is a stuck closed switch.

those trip relays appear to be the ones in the upper/right corner of the schem. When they trip, the pin relays around schem B11-13 power to release the pins to flip up.

you can stick paper between switch contacts to prevent the relay coils from powering to help narrow things down, or just poke around with a voltmeter.

btw, the pin action magic is the circuits controlling when the pin relays trip.

e.g. the 9 relay trips only when the 5 or 6 pin relay trips. There are no lane switches controlling the 9 relay directly.

since your issue is 3 adjacent pins, you have a decent chance the problem is mechanical - e.g. reset bar worn/loose on the 7 pin end. You could latch the pins by hand, but the bar won't do it reliably.

if your 9 pin is flipping up electrically, then you'd need to look at switches on the 5 and 6 relays. The wire colors you can get from the schem (black and J ... tho you don't know what color the (j)umper wire may be from the schem. All the jumpers in the game could be the same color).

note different switches on the 5 relay trigger the 8 and 9 relays, so you'd need multiple switch issues to get your symptoms if the problem is electrical.

I didn't pick the 7 pin as an example since that's a lot more complicated

Lucky you what a clean game...

So manually, the 9 Pin Relay will latch, which suggest the Latch Plate is okay..
I once had a ball bowler in a Moose Club, and at times a couple Pin Relays wouldn't latch.
After testing and insuring it wasn't from magnetized coil (latching) plates, I did a little
manual slow motion action with the Reset Bar, and it appear when it made contact with
switches' plate, as it was lifting, it appeared to be moving it slightly sideways as if the
bar and under plates (forgot exactly what they're called) were sticky..
I cleaned the bar and the underside of the plates (with Scotch Brite and a solution) then
lubed the bar with a film of Super Lube grease, and that seemed to do the trick. I now
do that to all United style reset bars that has a slight side wards motion as it lifts..
Not really saying that alone will cure the problem yours is having, but I found it's a
plus to do that procedure. I also clean and slightly lube (as long as it's metal on metal) the
bar's pivot joints. Also, I don't usually take the plunger out, but with it still installed, I like to
clean the Reset Coil's plunger with Lemon Pledge..

looks like the only adjust is how far the armature plate moves away from the coil top. You can fiddle with that by bending the hooked piece above the armature plate to allow the plate to lift up higher.

if the problem is the rod isn't rotating the locking cam far enough to engage the armature plate, see if there's something reducing the rod travel. Usually it would be something like the hole in the flat bar pulling the rod has elongated from wear or the rod has a groove worn into it.

there's a chart on the schem around H20 that defines the lane rollover switches. Which ones were you closing?

Mopar can correct if this is wrong, but I think the lane switches should cause the numbered trip relay(s) to trip, and one of the trip relay switches causes the pin relay to power and unlatch the pin so it flips up.

the pin state should always correspond to the trip relay state. If you manually trip a numbered trip relay, the associated pin should flip up.

also recall some numbered trip relays do not trip via lane rollovers ... they only trip when other numbered relays trip.

so debugging is kinda two steps:

1] what numbered relays trip when lane switches are activated

2] when a numbered relay is tripped, does the corresponding pin relay power and flip up the pin.

since you seem to be on [2] at the moment, I'd just manually trip a numbered relay and use a voltmeter to see what you have on the pin relay coil / switch.

the metal bars that are connecting the plates together are part of the circuit. The entire metal plate and mechanism for each pin is connected to the black 50V power wire. If you stick a meter probe on the yellow common wire and poke each metal plate, you should see 50V.

can't tell from the pic if the switch blade on the plate is a real two blade switch, or if it's just one blade. If one blade, then when the pin is down, the peg sticking out of the latch should be touching the switch blade. If there's two blades, then one is connected to the metal plate somehow and the peg needs to be closing the switch.

in either case, the blade with the jumper wire then feeds the 50V onto the coil lug. The other coil wire is coming from a numbered trip relay switch.

as soon as you figure it out yourself, the above will make more sense The good news is once you fettle one pin release relay circuit, all the rest work the same way.

In watching your video, it doesn't look like the armature is returning to its up position completely either: perhaps the spring isn't providing enough tension or the ears and/or the travel distance hook are binding the armature plate: the plate should move very freely.

I have a 1959 United shuffle alley, but these pin trip mechanism look identical to my machine. It is a two-blade, normally open contact stack, with the top blade having a solid brass wafer and thus making contact with ground through its mounting screws (I've attached a picture; it's not very good, but that top wafer is brass and not an insulator). When the pin is down (the armature is locked on the pin mechanism), the arm on the pin mechanism holds the contact switch closed, completing the ground circuit to the trip coil.
pin trip contacts (resized).jpg

are the 1st shot and 2nd shot relays working? Both need to activate to turn on the score motor and make stuff happen.

the 1-10 relay and bell need those relay switches closed to do something also.

looks like the score motor should only run when 1st shot relay activates if the strike/spare unit is stepped to a position that indicates you had a strike/spare on the previous frame.

are your strike/spare units reset correctly?

Okay. When manually activating the Score Relays, the Score Reels energize, so we know the Score Relays
aren't getting juice. Also the 1-10 doesn't energize when all Pin Relays are tripped. The 1-10 could be another
issue also, but one thing all 3 have in common is a make/break in the Start Relay. When the Start Relay is latched
(Reset), if the make side of that make/break isn't making good conyact, it'll prevent all 3 (Score and 1-10) Relays
not to energize, so you'll want to carefully check the contacts (along with their solder tabs) in the Start Relay, and
of course first make sure the switch stack screws are snugged. I'd also do the same with the 1-10 Relay..

So if the 1st Player's Strike/Spare Step Up is already reset before starting
a game, the Score Reels zero out properly?
Anyways, I'd maybe first concentrate on that other issue..

There is a make/break switch on the start relay and a make/break switch on the 1-10 relay that make up the 1-9 score relay, 1-10 relay, and chime coil switched return line.

Nice! What we've all been waiting to hear..

On the ball gate problem. Check the ball return push button make/break switch for a weak normally closed connection. The normally closed part of the circuit connects to the rear rollover switches, and they get their power thru a grey wire connected to a game over relay switch.
The normally open connection on the make/break switch bypasses the rollovers and connects directly to the grey wire. The ball gate coil can also be pulsed during the game reset sequence thru a score motor disc circuit.

On the easy strike setting once the ball rolls over the 1st rollover for the 1 pin, extra bowling pins will trip allowing for a not so perfect strike zone shot. The machine does it so fast that it’s hard to tell the difference vs normal strike.

The MBA bowler has a center extension, thus has 2 seams. I made additional legs and
placed them dead center of the seams (where the sections meet). The United 14 ft. small
ball bowlers have a (factory) center support underneath. On the Bally ABC Tournament bowler,
I made the same..
Years back, a Friend (that was heavy set) slipped and fell right on one of the MBA's seems, and
cracked it. Once I fixed it, I made the additional legs to prevent it from happening again.
Making and placing a couple legs under those seams would surely add insurance, or of course
you could also make a center support underneath..

There should be 4 metal rods that connect the 2 lane sections together. There are only 2 legs original for this game. There is no need to add or change from the original design by adding more stuff to it.

It's been a while since I restored a United big ball, but I do remember a couple long rods (long threaded
bolts) going through the 1 x 6 or 1 x 8 (whatever it is) that holds the formica. They're long. Maybe 14" or 16",
but when missing, I used threaded rod (a nut on each end). I believe they're the same diameter as the small
ball bowlers. 3/8". Not sure if I'm keeping the Playtime once gone through and set up, but if I do, for little as it
takes, I'll most likely build a center support like their small ball bowlers come factory with. Not a must, but if
there's a weak spot, it's at that seam. I did that with the Bally Tournament bowler. With the MBA, I built legs
to match the originals. It cracked at the seem, and I mean cracked. It was 100% unplayable. Made sure that
won't happen again.. Here's the Bally center support and MBA added leg at the seam..

IMG_0842 (resized).JPG

IMG_0843 (resized).JPG