On my phone and remote so it’ll be tough for me to help.
Can you describe the symptoms a little better.
Sounds like 1 player works fine.
4 player also works fine?
For a 2 or 3 player game, are the scores just rotating though all the score windows or is it actually playing a 4 player game?
Play each scenario game all the way through and count the number of balls that are played. 2 and 3 players should be 10 and 15 not 20 like a 4 player.
Are the balls played lights correct?
Separately, lift RH pf and watch what happens when the outhole is triggered. All the way through to the player unit.
Have you simulated advancing the player unit with your finger to see what happens?
When you cleaned did you confirm the staring position on the player unit sweeper and observe how it moves forward and return. You need to make sure all the units are centered properly. This is a common issue on all the units.
Do you have schematics and can you follow the diagram for the end of ball sequence.
Report back, or better yet create a new thread so you may get a bigger audience to help.