Any issues with the gumball dispensing a ball? Sometimes when you load the gumball machine, and you don't have that piece of plastic that prevents balls from stacking on top of each other it can cause problems. Thus there's one more ball in the gumball than normal, one didn't come out as expected. You lock a ball and that's when it knows its short a ball so it has to kick one out. Also try pulling all 5 balls and powerball out of the machine, factory reset, then load them into the drain one at a time, then play a game. See if this fixes the issue. That's all I can think of...

I would check the lock mechanism at the top/right of the machine (not the gumball machine). The kick out from that mechanism does not feed the slot machine, it simply kicks out into the right orbit. I haven't looked there recently, but I would expect it to have a switch or two and a kicker/popper. Make sure the switch(es) activate in test mode (with a ball). Make sure the kicker works correctly. Perhaps the kicker kicked the ball off the switch just enough that the machine thought the ball left the lock lane, but it still was inside. A bad or mis-adjusted switch in there is another possibility.

-Brannon

Had this problem. The switch 55 gumball Geneva was not registering along with a weak solenoid on the lock kickout. With one or two balls in the lock no problem. But the weight of the third ball caused problems. So could have been one or both issues but replaced the 55 Geneva and replaced coil sleave and spring and tightened down lock mech and had no more problems. The test mode worked fine for the lock kickout so that was no help in solving the problem, although it did point out the Geneva 55 error. A change in pitch might affect this as well. Also, as I remember, the watch for kickout happens in a multiplayer game where previous player has already locked. But I could be wrong on all counts and just got lucky.

Switch matrix problem most likely. Start with checking the optos and the kicker switch in the lock tunnel using the switch edge test in the diagnostics. Sounds like the first opto in the lock tunnel is bad although bad switch matrix chips like the ULN2803 or one of the LM339s can cause weirdness too. But I would check the opto first because, absent of battery corrosion, the optos seem to go bad more often than the other chips.

I'm pretty sure the "Watch for Kickout' only happens when the game doesn't sense a ball in the trough, so it has to give you one of the locked balls back to continue play.