I'm trying to track down the final demon in my BK2K restoration. Everything else now works perfectly, but seemingly randomly the game will forget it's in multiball after a single ball is drained. With two left in play. This happens for normal multiball AND Kings ransom. It happens about 50% of the time and I cannot determine any common circumstances that cause it. Everytime I think it might have something to do with something specific I'm proven wrong in the next test. Also, very rarely, about 2-3% of the time, the game will kick out a ball into the shooter lane when a glitched multiball's second ball is drained.

I've checked all the switches in switch test. All of them work, and none cause any weird switch behavior. No double registers, no unusual bouncing. Game works 100% other than this.

I found an old thread that mentioned one of his switches was wired wrong causing this behavior, but my game doesn't have the same wiring issues he had.

The game is running LA-2 roms until I figure out why it won't boot with my LA-4 Roms. But I can't find a change log to see if there is anything relevant.

I shotgun replaced all the trough switches, outhole switch, lock switches, and their diodes. Now I get consistent behavior... Consistently bad. When multiball begins, it immediately ends. With all 3 balls still in play. Jackpot never lights. If you get a ball up the ramp it counts as a lock. All switches test good, with finger and ball. At this point I'm desperately hoping getting the roms updated fixes something because this is driving me nuts.

The lock switch board has been serviced already. All diodes replaced, connector reflowed. I have tested more times than I can count at this point. The switches act exactly as they should in switch test.

I'll try replacing the female connector with crimp pins.

I'll try the ramp switch disconnect though. Haven't tried that.

Thats a....Great idea. I'll try that!

So I'm tentatively calling this one solved. It seems we had a perfect storm effect at the beginning where several problems contributed to the same issue.

#1 was a faulty switch/diode somewhere in the trough, since after replacing them all the behavior became much more consistant.
#2 was a bent metal. The metal U that makes up half of the lock was bent in such a way that the switches were not in a straight line, causing the upper switch to be harder to trigger. In addition, this bend made the balls able to travel slightly left/right. the strength of the 3rd switch was enough to trigger, then push the ball away far enough to open again.

Thanks to all who helped. These demons have some insane hiding places sometimes.

Special shoutout to darcangeloel who gave me the idea to disconnect the ramp entry switch, which made the game rely on the upper lock switch to start multiball. causing me to look at it REALLY closely and play around with a stack of balls in the lock.