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.

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

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Check this connector with the orange arrow pointing at it. Probably where the issue is.
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Suggest Re seating the cables on the Master Display Board.

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Good chance PIA is functions as its able to produce correct output at player 1 and player 2 displays good segment data, further distribution of signals is done on the Master display board after IC 6 which could be partially working and not throwing correct strobe timing at P3 and P4
Before changing the PIA IC 18 or decoder IC 6 or Master display, the signals need to be checked for full presence at IJ5 , IJ6 and, IJ7 and if a signal(s) is missing will need to be traced to the source by isolation using a logic probe.

Chris Hibler is a well known tech here that can service your boards - http://chrishiblerpinball.com/.

I've also used the Coin-Op Cauldron numerous times and they've always done good work. Good luck!