Hi Blair,
I'm not familiar with Pin2000 but the transmitter optos should be lit all the time in a WPC game so there may not be any 12v getting to the transmitters. If you have found all the switches are out in 2 complete columns then the ULN2803 is probably the culprit. Sometimes on WPC games, when the 2803 blows it will take out the chip connected directly behind it.

regards Derek