Hi —

Purchased a 1976 WMS Grand Prix and am running up against a head scratcher issue so I thought I’d put out this plea for help.

When the 2-star relay is activated (this is achieved by hitting two sets of drop targets), it allows for an extra ball to be earned by making an inlane rollover. Whether or not an extra ball is earned, all of the star relays are supposed to clear after a ball drain. (The star relay reset should happen regardless of whether one, two, three, or four stars have been achieved during that particular ball in play.)

So what’s happening is that after the ball drains, sometimes the two star relay resets, and sometimes (randomly) it does not. On the times that it resets all of the star relays reset, but when it sticks on, only the two star relay stays energized/stuck on. So for example, this can happen by having the one and the two star relays activated, and during the non-functioning ball drain cases, the one star relay turns off, but the two star relay stays on. Or say, if three star relays have been achieved and it doesn’t function properly after the ball drain, then the one star and three star relays deactivate, but the two star relay stays on. During the times that it works properly, all of the star relays reset when the ball drains. I’ve gone through the switches that I think should be connected to the two star relay, and tried to ensure that the switches are all working properly, but the problem still is happening randomly. So it’s really got me confused since the randomness doesn’t seem to have any pattern from what I can tell by trying to troubleshoot this manually over and over a bunch of times. Any ideas for things that I can try to fix this? Thanks in advance for any ideas for help you might be able to provide.

Thanks Mark—it stays locked on when I cycle the power off/on. I can manually disengage when it’s off (but not when it’s on because it’s still energized).

That was it! Well, pretty much the same idea. After pulling off the armature, it was obvious that some old oil or grease had gummed up between the armature and the frame of the relay. I cleaned that up and shined with some ScotchBrite and it works perfectly so far. Thank you again Mark for helping convince me that this wasn’t an electrical issue (and to the Pinside community for making the EM Tech forum so helpful in general).

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