Working on a Bally Air Aces. Here’s the problem, a one player game works as it should however when you start a two player game at the end of the second player ball the game advances to the 3rd player, at the end of that ball it brings up the 4th player. At the end of that ball the game stays on the 4th player. I keep thinking this is related to the player up unit as the player up coil keeps firing after each ball except in 1 player mode. The player up reset coil fires only at game reset. seems to me this coil needs to be energized after the second player ball drains. Anyone seen this in a Bally EM before?
Thanks in advance.

thanks very much! I looked again at the player unit and found one of the wipers was not making good contact and was very slugish. Cleaned everything and adjusted the contact and that fixed the problem.