Working on this game for a friend and I don't have immediate access to it but here goes. The game seems to be running fine when you load three balls into it but when you try to add the 4th and then start a game it feeds two balls into the shooter lane? This is the first time I have worked on a 90's bally so I'm kinda stumped on where to start with this issue. I did go to switch edge test and verify that the opto board switchs are working for each ball in the trough. What else should I check? The software looks like it is Rev 1.0 I believe the newest version is 1.2. I see that the revision fixed an auto plunger issue not sure if that will help?