My Godzilla Pro recently started exhibiting several problems related to ball count. For example, I would be half way through godzilla multiball with balls on the field when the flippers would turn off forcing the balls to drain, or the game would not eject a ball when the ball save was triggered. I suspected that the game was somehow losing track of the balls in play.

After some menu exploring, I found the ball trough test. With the door switch pulled out to activate the 48v power, a noticed that position 20 and 21 in the trough test were intermittently flashing. Although position 20 is ball 1, I believe 21 is the ball jam sensor just above ball 1. With 6 balls in the trough and no action, position 21 should show open, not flashing intermittently.

I simply pushed on the signal connector to the trough circuit board, and the ball position 20/21 flashing stopped. Loose connector problem. Easy fix, but this would have made me insane if I didn't find it quickly.