Quoted from dluth:Just to report back on this...thanks for your answers you were all right it is an opto problem. Column 1 and 2 in the switch matrix were green, which I assumed was good, but of course is bad (there were no balls in the trough at this time).
I have actually fixed the column 2 optos by wiggling the connector at J202. A bit dodgy as a bit more of a wiggle and it could go back to bad again, not sure how to fix it permanently.
With column 1, the trough optos, they are still out. I have reseated the connectors at the trough, at the back of the board chassis and at J200. No change. Not sure what to do next...
Do you have a multimeter so that you can read the +5vdc at the trough? Also, check the two blade fuses near the front edge of the I/O board. They are both tied to the switch matrix. If you have a meter, do continuity check between J201pin1 on the I/O board and the same wire on the switch connector at the trough receive board. Since that wire (green w/black trace) is common to the entire column 1, it may be broken somewhere in between.