Quoted from Roamin:
I'm fairly new in the pinball world, but I saw the very informational video on shorted diodes and what could happen, triggering different switches, and how you make a box to identify them.
During multiball, and casters club is locked again, the ball that was locked is actually not waiting in the reel, but rather in the catapult, ready to fire. So the catapult switch is toggled at that moment.
You then trigger switch spinner.
I think you might have a shorted diode in one of those 4 switches in the image I posted. Spinner and Bob tilt are on the same line, and match that with catapult at the bottom that is closed. Probably why it only happens during jackpot shot.
edit: Actually the shorted diode should be out of 3 and not 4 possible switches , trough 1, catapult or spinner. These 3 switches are really abused in this game so it wouldn't be that surprising I guess.
thanks a lot for the feedback!
I actually found a screw in the jackpot saucer, I guess that was doing the short.
Removed it, tried like 6 multiballs, no tilt.
Will keep on doing some tests, but finger crossed that was the culprit!