Have a Stern FG that is not registering switches correctly and the 4 bank and single bank drops. The original 4-bank would only register on switch 2. Replaced the Opto board with a known working one and none of the switches will register, however the board does have the correct voltage, and the optos are working correctly (tested output). I tested wire continuity from the switch to the SAM board and all circuits tested fine, so I am sure the new optos boards and wiring are fine. All other switches work fine as well. Board connectors were tested and all pins re-flowed just to be sure. Anyone have a suggestion of where else to look? I do believe from testing that the original 4 opto board was probably bad as I could not get any reading on 1,3,4 optos like I can on the replacement....is there any history of these optos going out and messing up the main board? I appreciate the help.