The issues I'm working on are switch-matrix related and switch wiring. The A in the left side PAC Targets, the Top Left Saucer switch wiring, and the middle upper drop target have been problematic and intermittent. Some other nearby switches also occasionally are intermittent.
Replaced diodes on those switches, cleaned switches, they tested in continuity. Traced the row wire (Brown and whie striped) between switches and back to the MPU, connection is good there as well as components on the MPU. Perhaps a frayed wire somewhere....
The real head scratcher is that a number of the switches have caps on them, whereas the schematic does not say they should have caps. The upper left saucer switch had one, the middle upper drop target did not, the A target did too. I followed the schematics and removed them on the saucer. Now I cannot get any of those three to activate at all. Re-added the caps, but cannot get them to work again. My guess is a frayed wire, but I just want to be sure I have my switches wired properly before replacing wiring.
There were a number of repairs done previously that were questionable, and having detailed photos of the entire underside would be pretty helpful to compare with. I have no issue going through the schematics, but I'm up against the clock now with getting this finished by x-mas.