I have ya'll beat.
Had one ball locked in Crypt, and was starting a new ball. The ball did NOT rest on the shooter lane, instead it bounced off the wood and was resting on the edge of the trough outhole. So the game then kicked a second ball out. BOTH then landed COMPLETELY on the shooter lane. So it should NOT have TRIED to kick the third ball out, yet it did.
After this, things went a little crazy. With three balls on the playfield, the autolauncher thought I shot the right Path, and started Cold Ethel. The fourth ball was released, so I had a 4-ball Ethel going on.
Eventually got down to one ball - and drained it.
Ethel continued. I had to open the coin door, and manually eject a ball from the trough. Played it a little longer, and then it drained again. The game then jumped back into 'single' ball mode (Ethel over) and then immediately went into Bonus.
Rest of the game, everything worked fine.
Recommendation: In the switch test, instead of just telling me 'balls missing' or 'all balls present', let me SEE which of the 4 switches are registering. If one is stuck on, I'd like to know which one.