My Air Aces is acting peculiar and I suspect someone attempted to make the game freeplay at some point but didnt do it right.
When initially turned on, the Game Over Interlock Relay trips, and the game is put into Game Over. Pushing the credit button makes the credit relay pull in, but nothing else happens. Activating either of the two coin microswitches makes the Coin relay pull in momentarily, and it starts a game. The machine cannot start more than a one player game. When the coin microswitch is hit during a one player game, the Coin relay pulls in momentarily, and that's it. Everything appears to reset fine.
I did go through and clean/gap all switches, clean/lube the steppers. I also did solder a wire between 2 of the contacts on the credit unit to properly set it to free play.