I've had my new WOZ for a few weeks now. Everything seemed fine until just recently - now when I lock 3 balls to start Emerald City Multiball, about half the time the arm won't raise. The lock arm doesn't seem to be rubbing against anything and it raises OK in the test menu.

I keep trying to diagnose it further but the problem has a mind of its own. I could be in the middle of a game, ECM won't start, the machine goes into search mode and the arm still won't raise, so I release the lockbar to get ready to remove the glass and inspect further. Then all three balls get released and I'm trying to play multiball while using my gut to keep the glass from sliding out. (Maybe it's a special game mode.)

Or I restart a game and the lock arm still won't raise so the game can't start. So I remove the lockbar and glass to try inspect further, and as soon as I begin to pull out the playfield the freaking arm raises as if to say "Oh no you don't! You're not going to see what's going on in here!"

My best guess is that the coil is overheating, but I'm not sure so I don't know if replacing it is the right solution. I tried lowering the time interval the arm raises from 250 to 235 milliseconds, but it didn't make a bit of difference. It's also using the newest software version (6.61).

Sorry - didn't mean to double post.

Yeah everything looks connected. It works half the time which is why I thought heat may be an issue. But then my last test had me power on the machine and immediately lock three balls by hand, but the arm wouldn't raise. So I didn't even play the machine for a long time for it to start acting up. (But as soon
as I pulled the playfield out the arm raised.)

I might have to remove the munchkin huts to see what is happening in-game.

DCFAN - I'm thinking that could be my problem as it seems to fit with why it suddenly works when I attempt to move the playfield. (By doing so, I'm jostling the balls a bit and adjusting the angle of the arm where it is suddenly easier to pick up.). I'll give this a shot whenever I have time.

I've had some time to play around with this. First, I can say DCFAN's diagnosis was definitely the issue. (If the arm wasn't lifting, I just needed to raise it a bit to feel the magnetic force take hold of it.)

But I'm wondering if there is something wrong with the coil. I say this because it worked fine when I first got the machine, then after a few weeks it lost it's strength half the time with locked balls, then (after my original post) progressed to the point where it couldn't even successfully perform a test with no balls locked. Now it seems so weak, I have to bend that metal plate attached to the arm to the point where the coil can now grab it, but the arm has to be so high it can no longer stop the balls so the whole fix is kind of irrelevant. I probably spent a couple of hours bending the plate and testing, trying to match things up with the picture showing the solution - but if there's a certain sweet spot I need to find, I haven't found it yet. The arm just doesn't properly catch the ball anymore when lock is lit.

And then there's another concern. If the arm doesn't raise when a ball is locked, I've come to realize the coil just gets hotter and hotter in a continuous cycle of trying to raise the arm - and that doesn't seem like a good thing at all. Do I need to just stop messing with this and get the coil replaced?

Thanks Lloyd. That does make it easier to bend the arm and experiment, but I'm still not having the same success as others with this trick. In the photo below, that's pretty much the minimum height I've got to set the arm in order for it to raise every time in a coil test. And even at that setting it can't stop balls from just rolling through at the slowest speed and not locking.

0724182350 (resized).jpg

Alright thanks everyone. Last night, despair was setting in but today I have a new glimmer of hope. I won't be able to work on it for a few days so I'll revisit this next week.

Just wanted to report back for future reference if anyone else deals with this. I believe I finally got it working right, and I agree that bending the entire coil bracket forward makes all the difference in the world. I also had to adjust the metal tab under the arm and the metal plate connecting the arm to the coil housing, but I may have never needed to do this if I started with the coil bracket first.

The coil bracket also only needed a very tiny adjustment forward. (At first I bent it forward too much. I could lift the lock arm with my hand and the balls could clear under it, but the actual coil wouldn't lift the arm this high. Bending the bracket back a bit actually fixed this little problem.)