New game to me. Test report - check switch 56 - Bookcase Opto 4. When I check the switches, none of the switch in the row 6 - White-Blue register.
Unplugged the Opto board, and it made no difference. We have checked for continuity and power on both sides of all the switches for that row, all look good.
Replaced I/C s, and still nothing. Any ideas??

u18, u19 and u20 just for good measure.

when the connector was plugged into J207 I also had column 6 out. When moved to J206 it came back. This problem started as an intermittent problem with the game shooting out multiple balls. At one point I unplugged the optos and plugged them back in, and that switch came back to life. A few games later and it went back to the same problems

no j206 an j207 are for the colums, and j208 and j209 are rows. I had both a column and row issue, but fixed the column issue by moving the connector

I have checked for power at the switch, and have it on all the switches. if the connector was bad, I would think that I would not have power at the switch?