I have a brand new AC/DC that has started having this issue, was built in August, machine may have 50 plays on it total. Thanks for all of the information. None of my other Sterns have this problem at all.

I mentioned it before, but my Avatar mech and all the parts look identical to me and it has never had any issues that I can recall.... it also seems to have a similar amount of slop. Not sure exactly why it does not have the same problem. There may be a bit more to the fork separation and angle and such, but it sure seems that AC/DC has a big share of this problem.

I actually found the culprit on MY personal machine... If you look at the pics on this thread compared to MY pic of the linkage you'll see that the spring on the shaft on mine was riding above the linkage and WAY up on the blue portion. Even with the "rubber shims" thing I'd still get a lot of launches that weren't "full". So...after re-looking at this thread and noticing that difference I rotated the spring back around and compressed it below the blue part and now it is consistently launching to the juke box. Figured I'd share because this part of the machine seems to have many small parts that can impact its performance.

The issue here is pretty simple and very common for Stern games from about Avatar forward. The plunger going into the coil is sitting too far out of the coil at rest. Your Velcro piece is effectively pushing the plunger into the coil more, allowing the coil to properly "grab" the plunger for a strong engage and ball launch. Without the Velcro piece to push the plunger more into the coil, the coil doesn't pull the plunger in effectively enough to get a good launch.

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Rob Anthony
Pinball Classics
http://LockWhenLit.com
Quality Board Work - In Home Service
borygard at gmail dot com

This seems like a odd solution to fix the issue, kinda like using duct tape to stop a leak. Isn't there a better long term solution like perhaps swapping the plunger to a longer or shorter stem and thus engaging better?

Does anyone know if this issue ever get resolved? My Luci is having the same issue. I tried the Velcro and the some other risers but that has not seemed to help. Is it the "play" in the linkage that is causing the issue? Thanks very much for any help. I am a total newby and I really suck at keeping the ball out of the Left and Right drain.

The ball was hanging up on the switch wire on my luci.

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So was the fix to move up the "forks" (sorry don't know the correct term) by placing the Velcro on the underside? I guess this would give the forks a quick start so to speak.

Thanks

I had to bend the switch wire down a bit. When the switch was fully closed, the wire was still poking through the slot about 3mm. On a light plunge the ball would bounce on the switch wire and not go anywhere. Sooner or later the switch would have broken. I did adjust the forks a bit.. The autolaunch seems to work ok now.

Rob

For me it seemed like a combination of things could cause it. Bushing rotation, adding rubber to the bottom side as shown, tweaking fork spacing and position. Found out in the end that everything had some degree of effect on it. Ultimately on mine the shooter rod tip getting clipped by the auto plunge was the biggest culprit, but the other small things worked enough for it to be ok for awhile. Once the tip is rotated or ground down more it has seemed to be good for a long time now.

Mine has been working fantastically since I made the brass bushing and took the slop out of the mechanism.

I just tried this on my ACDC and used 2 pieces of adhesive mounting squares on top of each other as directed. It's working well so far. Thanks for posting this solution. Otherwise I had to slightly push the plunger in during auto-launches for it to shoot into the jukebox area.

Just fixed this on my Metallica pro using felt foot pads cut thin to fit between the metal prong and cabinet wood. It works great now, although if the auto launches ever get weak I will replace the felt.

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Nice... great lo-tech patch. Seems like these things can get sloppy due to many factors and various things can fix them. One thing I don't get is why my Avatar machine has never had this problem... not complaining, but it looks identical. It might have something to do with the fact that in Avatar you plunge the ball for the first launch always and the only time auto is used is for quick drains and multi ball. Over time those first launches add up.

I haven't read this thread thoroughly, but my AC/DC premium auto plunge became progressively weaker until a point where perhaps only one in three balls would reach the "trap' at the jukebox, and many would only reach a point halfway up the playfield. Upon inspection, all mounting screws for the plunger assembly were definitely tight. I made two adjustments...... 1) I slightly closed the gap between the two forks which contact the pinball, and 2) I lessened the free play in the lower pivot of the plunge forks by removing the circlip and spreading the U bracket a little. Don't know if just one of the two changed would have sufficed, but every plunge now has the ball reaching the "trap'.... and usually reaching it convincingly hard. I hope this helps. Rob

It is the nylon bushing on the auto plunger assembly that causes the issue my Metallica had the same issue and my father machine me a brass bushing to replace the nylon bushings and ever since that was installed I haven't had one week shot

I've found as many as 3 different variables that can cause the same issue.. currently my plunger tip every now and again contacts one of the forks if the tip on the plunger rod is rotated in the "wrong" position... usually a quick twist left or right to a place that is more worn lets it kick out good.

I picked up an x-men that had this same problem, and tried a couple different things. At first the extra velcro (I actually used a cabinet door bumper, but same idea) underneath seemed to help a lot, but then it started acting up again. I tried taking it apart and cleaning all the moving pieces, but that actually made it worse, probably because it went together again a bit out of alignment. What finally has seemed to fix it was a combination of two things. First, I made sure that both of the auto-plunger arms were touching the ball when it rests at the bottom of the shooter lane. Second, I tried to adjust the arms to make sure that when the ball rolls down the shooter lane to rest against the auto-plunger it doesn't move the arms around at all. As others have mentioned, there is a bit of play in the bushings, so if things are off center it seems like the ball will cause the arms to go out of alignment. I didn't get this perfect since the arms still shift a very slight bit when the ball hits them, but it seems to be good enough. Hopefully this will help out others who are fighting with this issue.

I've had issues with the auto launcher in many different versions of ACDC premium and all the tweaking you try will never be better the. The following solution. Just order the newer auto launch assembly that comes on games like mustang premium and IMVE. It take some tweaking to get it to fit but I I stalled it in about 30 mins and every one if my auto launches makes it Into the scoop every time. 100%!

Here is a pic if the assembly

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I had the same issue that many have had with the AC/DC auto launcher. Sometimes it works okay and other times super weak and can't even launch the ball in play. I bought my game brand new and within a few months the auto fire launcher was having the issues. There has been many solutions posted and I've tried some of the easier ones like adding felt and adjusting the forks, but nothing worked long term.

Finally got tired of the weak auto fire plunger and called Steve Young at the Pinball Resource. SUPER nice guy and he suggested an easy cheap permanent fix. He sold me a slightly stronger coil for $7.50. I put the coil in and so far it's working good. The ball appears to auto fire a little harder and so far even the weak launches make it in to play. But it still vary's from perfect auto fire to soft (but in play). I used coil AE-24-900 and just removed the diode when I installed it. I probally should have used even a little stronger, but this fixed my issue and I'm happy so far.

Thank you to everyone that posted solutions. This site is fantastic!!!!!! If the previous solutions above haven't worked for you then give the stronger coil a try. Worked for me.

To follow up with my post, adjusting the arms to minimize their movement when the balls hits them AND ensuring that both arms are touching the ball was the key to getting this to work on xmen. It's been working perfectly since I did those two things.

That's great but how do you adjust the arms?

I used pliers. Bend the arms until they are just right. It took a few small movements but it made a huge difference. Just do it in small steps to make sure you don't make it worse.

What "tweaking" did it take to make the new fixture work? Did you have to modify the game or the new launcher? It sounds like your different launcher is the best bet for anyone still having issues. I'm assuming the two fork design is the problem? The stronger coil I put in is working good, but I wonder how long it will stay working if the forks are the issue?

The new mech has a mounting stud that fit into a hole in the newer play fields that uses this auto-launcher. So I had to drill a small hole for the stud to fit into. Didn't take long and i've never had an issue with the new mech.

To the left in the attached photo you can see where I removed one of the snap rings on the auto launch mechanism. This seems to give it just enough extra play to make the shot. I've never had to bend anything or fabricate any spacers. I did this to mine when it started getting weak about a year ago and it hasn't failed since. And before you ask, no, the pin doesn't back out nor does the bushing. It's worth a try if you're getting frustrated.

It's not the best picture, but it's the closest snap ring to the front of the machine on the right side of the mechanism.

Dan

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So there is more than one snap ring on the mechanism? It's hard to tell from the picture what you removed? The white looking C ring? Thanks for sharing the info.

Yes, that's where the snap ring used to be. The white "C ring" is a bushing and the snap ring was at the end of it.

Found this post after researching a similar problem on my KISS LE.

What I tried:

- velcro tape behind link (didn't work)
- replaced nylon bushings (didn't work)
- increased strength on coil in settings (didn't work)

What DID Work:

1 - Removing lane cliffy's previous owner installed (was messing with the launch angle)
2 - bending forks on ball side closer together. Like an ARROW /\ but still spaced apart with good ball contact on both sides
3 - Bending forks on the COIL side far APART to remove any play on either side and to keep the mech tight.

If you don't have lane cliffys to remove, focus on 2 and 3 and you will be DONE. My ball would barely make it above the plunger lane before and now it makes a full and fast rotation around the back of the machine to the KISS pops on the left!! Big difference!!

Hope this helps...

Time

None of these problems are what I'm experiencing. My Star Trek pro from a cold start has a nice strong auto launch. After a game is started regardless of whether or not you play, it get weaker and weaker until after about 10 minutes it can barely make it to the playfield. No binding at all. Not a fork or slop problem. Coil, sleeve and spring all new. Plunger/link and coil stop all good. Coil not over heating and driver MOSFET Q2 not heating up. WTF?

It's BS - my RCT is bow acting up - waiting for a new coil and shooter - stupid

Having this issue on an Ac/Dc I just picked up. Do we have a final solution yet? This thread is just confusing