Here's one I haven't seen before.
During power up or tilt the "game over" light is off. I start up a game, the sequence is flawless. However once I'm on ball 1 my "game over" is lit. I've been playing around with the associated relays and the seem to be adjusted well. The system will not advance past ball one. Both my trough switches are good and ball advance unit works great during reset sequence. I can add up to 4 players. Playfield features reset after drain but stays in ball 1. The stepper in the back does not seem to put in any effort to advance ball so being gummed up isn't an issue. I can add a quick video here if that helps (or add more data when I'm more awake). Spent a bit of time making sure contacts are clean and no broken wires. Could there be a bad connector or contact somewhere? I haven't paid too much attention to the playfield units since scoring seems to function well.
I haven't owned this machine with it working properly could this have been a botched repair from a long time ago? Came out of a basement where it sat for a long time. I've spent a little time cleaning up some of the stepper units since I also had some reset issues. As of now I can start a new game every time without it hanging up.