Sounds like you have a bad opto... Mine had the same issue, the opto on the right under the vengeance was bad on mine. The good news is that Patrick at stern will send you new opto's no problem! the bad news is that the right opto is a PITA to get to. I would double check the connections under the playfield where the optos plug in (reseat them) maybe you will get lucky.

Mine also did that but I just adjusted the spring so it's tighter and holds the target in place

Forgot to mention I also tried this (see pic) before replacing the opto but it didn't help my machine.
The little board the opto attaches to on my machine had a bad connection causing it to randomly trigger. If I put the game in switch test mode the opto would randomly trigger even when I wasn't touching the machine.. I believe it was switch #33
image-195.jpg

I had this problem, or a similar one, and it wasn't an opto or switch or anything, was purely mechanical. The screw on the drop target that's on the same side as the spring was pushing it so it wouldn't latch properly. Weird behavior like phantom hits, popping up and down rapidly etc. Sound familiar?

My solution was to take out the screw on the spring side, and feed it back in from the other side, so the head wasn't interfering anymore. It won't "bite" anymore, threads won't catch on the plastic, but the other screw holds it in place, so it work fine.

Ever since I made this fix (Rarehero gets the tip for this being the problem, I think he found a smaller screw head though) I haven't had a single repeat of the issue.

Yup, this is most likely the issue, not the opto. The target is getting pushed by the screw head. I found a screw with a slightly smaller head and haven't had the problem since replacing the stock screw with it.

it must be the Enterpirse effect - my STTNG top target does the "up/down" thing all the time. Have to see if it's similar. Picking up my STLE NIB tonight. Small diversion in blood flow>.....

Thanks. I had the exact same issue. The latch was only holding the drop by about a fingernail. Added washers and back to normal.

Hey there, can I ask you guys whether you had to remove the whole drop target assembly to insert the washers under the screws, or were you able to do the fix with the assembly in place? It sort of looks like if I can get the right angle with a screw driver, I might be able to loosen the screw and slip a washer behind it. But, I figured I would ask how others did it before giving it a try myself. Thanks!

Remove the assembly. It is only a few screws and will be much much easier to access. Tales less than ten minutes.

Thanks. For some reason, it looked more complicated than that. Good to know that it is fairly simple.

My advice is remove one screw from the black spacer lip and loosen the other one. Put the washer in behind the black spacer and place the screw and then remove the other one. Hope that makes sense.

It does. Thanks!

Do you remember if you had to disconnect the electronics when you removed the assembly? If so, were they just plugs?

Yes there are plugs, no soldering needed.

Thanks. All of my prior experience was with an old Bally. Nothing was easy with that.

Easy fix with the washers.

Anyone able to take a picture on how the washer are suppose to be installed. I am not quite getting it as my drop target still is going up and down on its own.

Take out the two screws that hold the plastic shelf to the bracket and put the washers between the shelf and the bracket. Reinstall screws.

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Thanks!

It works well. Another common issue is that the spring tends to pull the target to the right and it may hit the head of the right shelf bolt and that keeps it from seating well. A flathead screw will fix it if yours still has issues.

What size washers?

Look at the pic. They need to be small washers. Backing washers for rivets will work if you have any.

The Stern bulletin says 1/16". I still have to try this myself. My drop target is getting worse by the day. My after Thanksgiving project . . . .

#4 thin washers work great

Glad this got revived, just started having this same problem. Stupid pinball fixin when I want to play!

Just fixed the issue with mine by putting the washers in place. Worked like a charm. I'm always amazed when I successfully fix something on my pins (especially without breaking something else).

Sorry no pics atm but here's the easy SKB lazy way of fixing this (since it's a PIA to get to those screws):

With the playfield upright, it's the screw on the left that needs a washer. Right one doesn't need it. Get some diag cutters and cut a small space in the washer (about 1/4 of the washer). Loosen the screw but do not remove it. Squeeze the washer in, tighten the screw. 15 mins fix. It's a little tough to get the washer in cause space is so tight. Just be patient and have a magnet handy in case you drop the washer.

SKB

That will work.
But I had no trouble by myself as the entire mech comes out with only 4 screws and two molex plugs.
Also a good time to clean the opto while you have it out.

Well, I spoke too soon. I eliminated the problem with phantom, repeated hits. But, I created a problem where every once in a while, hitting the target wouldn't register a hit. May theory is that the 1/16" washers may have been a tad too thick. I found a thinner pair of washers lying around the house -- call them 1/32" but I don't really know. Anyway, for now, that seems to have worked. (Of course, I thought I had this fixed yesterday, so I need a bunch more games on the machine to tell for sure.)

When you remount the assembly to the Playfield take care to position it so the target is clear of the playfield. It must be able to get knocked off the shelf and if there isn't enough clearance you will have the issue of it failing to drop when struck on occasion.

Maybe that was the problem, but what do you mean? There seemed to be only one position to put it back in -- I just aligned the holes and put the screws back in the assembly to mount it.

Yeah, I'm having that same problem too. Might need to try thinner washers.

There is no real adjustment, just tweak it as you tighten it down. It must have clearance between the target and playfield. You may have to go with thinner washers if you can't get clearance.

I found that it was an issue with the rounded head of one of the screws preventing the drop target from "latching" to the lip that it rests on. (The drop target can move VERY SLIGHTLY off-center from time to time.) I replaced the round head screw with a countersunk one and haven't had any issues since. No washers needed, but each case may be different.

Hope it helps!

_{Post edited by MrDo: Clarification}

I'm still getting the occasional hit that is failing to register, though it seems less frequent with the thinner washers. Maybe I need to try just one thin washer on one side. There's probably a sweet spot that is a bit machine dependent. Kind of frustrating.

I feel stupid, but I'm just not getting this. My target seems centered in the slot. If it wasn't clearing the playfield, I don't think it would work 98% of the time like it is doing.

I had done the washer method quite a while ago - traded ST to a local guy - he gives me a call a week later stating the drop is having the same behavior. Take out the drop unit and the plastic ledge was shattered. I'm going to try a thicker shim that goes across the entire ledge so it doesn't have a chance to break again.

I added washers, prevents multiple drops on one hit, but now a really firm hit does not cause the target to drop at all. Makes for STM drain.

Do you think this is because the washers are too thick? Or is there anything I can try to fix this behavior?

It's most likely a clearance issue with the target and the playfield. There has to be enough room for the ball to knock the target back off the shelf. If the washers are too thick, it can cause this, but you may be able to tweak the position of the assembly a little as you tighten it down to get clearance also.

It can take two people to diagnose this, one to shoot, and the other standing at the side of the game watching the drop. That's how we figured mine. The drop was too far back, probably because of the washers, and practically pressed up against the wood of the hole. Ball would whack it hard, but it just couldn't get pushed back far enough to reliably drop.

You can't see this from the front of the machine, why having a second pair of eyes helps.

We took the assembly off and bent it slightly, and installed it keeping it as forward as possible while tightening the screws.

Problem solved, had a league event with 35 people playing it all day, no problems.

My drop target started acting up again yesterday. Turns out the black plastic shelf broke in half. $3 to order a new one so not bad but I believe the problem was I used too thick of washers on mine. Just thought I would let others know who have done the adjustment.

The guy that bought mine has broke the plastic shelf twice now. He had a metal one fabricated - don't know how it is working yet. 2nd time I put a thick fish paper behind it and it still broke.

Thanks. I was thinking about making a metal one as well.

This just happened to mine. Where did you order the black plastic shelf? Directly from Stern?

Thanks.

Aurich, I'm still having this problem of an occasional hard hit not registering. Can you tell me how you bent it? Just with your hands? Also, in what direction? I think to get the target to lean forward more, you need to bend the assembly from a right angle to a slightly obtuse one, correct? Thanks!

My shelf just broke as well -- it is cracked but still functions for the moment. I emailed Stern. Amazing that in this day and age, a simple drop target is giving people so much trouble.

Pinball Life has them

Thanks!