Need to narrow down which coil or relay is stuck on first, and then can debug further. Check the points relays (N, M, L), and see if one is stuck on. But don't leave it on too long or the coils will get too hot.

The Ball Release coil is activated by the Trough switch, and a normally closed switch on F. So as long as F isn't activated, the trough switch closing should be enough to release the ball, except... F is activated by the Trough switch!

F is held activate until either:
- score motor 1B switch opens
- switch on V relay opens
- make/break switch on K switches (to close the path to F)

V activating would be the normal path. It's activated also via a switch on F, and normally closed switches on H, I, and at score motor 1C.

So check if V is activating, and if it isn't, check the switches on the path to V. You'll see them on your schematic at about 12E.

It might be vibrating the trough switch? Hard to say, as there's nothing on the coin door directly that's in the path.

And the pop bumper relay is not energized when the ring is stuck down?

Can try swapping plungers/stops with another pop bumper that's working too, and see if the problem stays or follows them. Or, a new combination may just work.

Completely different circuits, so no, not really.

Just your basic voodoo then.

Have you confirmed that the coil itself in the V relay is still able to work? (energize). If you press it by hand and it causes the score motor to run, but V doesn't lock on, that may suggest the coil itself isn't able to energize. (Although I've not looked at the schematic yet to even see if V has a lock on path.)

But if it worked for 10 games, and then the coil failed, that would be one possible way to fit the symptoms.