put the game in display test and see what the count is and if numbers are certain displays are skipped and others repeated.
I think you are going to have a connector issue at the MPU on 9 pin plugs across the top of the MPU.
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Quoted from RXTbone:Any ideas why re-seating the door/diagnostics plug would switch the 3d and 4th player from 333333 to 222222?
because that plug is nearby the display digit count encoded data plugs and it made the board flex breaking/opening an intermittent connection. Probably broken solder joints on the connector pins. Take a picture of the back of the MPU board and we can probably see the bad solder.
There is 4 bits from the MPU that get decoded by a 4543 chip to form a number. Here is the display decoder chip truth table. Note how bit B can change all zeros (what it should be) to all 2's. If B and A are wrong all zeros can turn to all 3's
Check this connector with the orange arrow pointing at it. Probably where the issue is.
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