Does the scoring issue happen with all four players or only 1 player in particular?

@emnewbie, you can look at the same reel on player 2-4 and compare to player 1 to see if any of the gaps are incorrect.

Work the player 2 100's reel by hand noting the position of the switches as you go through the numbers and then see if player 1 behaves the same.

Also, just because a switch looks open (or closed) don't trust your eyes, use a multimeter to ohm it out.