Just an update. I stopped over his house and took a look at it a couple weeks ago. I tested continuity back to the opto board. That tested fine. We replaced the optos and tested for good measure that they were lit (they were). I disconnected the switches off the CPU board and tested all the rows and columns there, and they tested good. At one point all optos and switches were working.
I believe the CPU row and or column connectors may have some corrosion, I recommended he replace those, and also I am pretty certain the similar connector on the opto board is suspect.
Strummy, please post a couple pictures of the front and backs of those connectors. Also someone post a link to the connectors and the tool to punch the wires down. This is not a typical GI style connector, it uses the much finer small wires. I don't think pinballlife has them. I'm guessing maybe greatplanes electronics but don't want him to purchase the wrong connectors.