From your description it is a connector or connection issue. The digit signals are daisy chained from player position 1 thru to player position 4. So if the digit is shown properly on player position 1, then the wiring and connectors are probably good at the MPU and player 1 display. If the signal is lost at position 2, then like the gentlemen above suggests reflow/repin the connector at that spot and see if that takes care of it.