Quoted from Schwaggs:
Remove the driver board connector special solenoid drive J12. Confirm the pop no longer locks on (if it does you have a wiring problem).
Removing J12 stops the pop from locking on, so no wiring problem.
Remove the special switch input J13 from the driver board. If the pop still locks on, you most likely have a bad driver, pre-driver or gate on that circuit. If it no longer locks on, you have a switch or wiring problem or the capacitor on that pop has failed shorted.
Removing J13, the pop locked on for a moment, then released and stayed that way. I realized that this was maybe residual charge in the capacitor from the previous lock on? In any case, it seemed to stay NOT locked on with J13 removed. Using your thoughts above, I immediately thought of a switch-related wiring issue being the culprit.
Resolution- If you look up in my post#6, you'll see on the edge of one pic that there are a couple of wire nuts near J13 on the Driver board. Realizing how hacked up other stuff was by the former owner, I should have immediately looked at these as soon as I got the game. Sure enough, the Orange-Brown wire associated with the Left Pop that was locking on was one of the wires that had a wire nut on it. A quick twist of the wire nut and it fell off, revealing some wires that were clearly not twisted together very well. I properly repaired the wire, and got rid of the wire nut. Going to do the same for the other wire in a similar state, even though it's not causing issues currently.
Update - Sadly, this didn't fix the problem like I hoped. It appeared to, but only briefly. The pop is still locking on, even with J13 removed. Every now and then it will not lock on, but most of the time it does.
Best guess, when the pop coil went bad and started locking on, the guy probably wasn't sure what to do. He started cutting wires in various places to try and eliminate the fuse-blowing problem, and after that didn't work, tried repairing the cuts with the wire nuts.
Next Up- 3 bank drop target in the back right of the game isn't resetting. Solenoid tests good, so I'll start doing some other testing to see what's going on. I know these are supposed to reset when all the targets are down, or on a ball drain, but they don't ever seem to reset. The lower set of drop targets reset fine, but don't seem to score. Both drop banks likely need a good cleaning and tune up.blackout_sol_switchwires (resized).jpg