As previously, removed one component at a time and cleaned up, tested, replaced, and rewired. The panel light for the generator (or alternator) was missing one of its contacts. I was able to fit a narrow strip of 0.010" brass fit in there perfectly and get the light working again. Continued replacing wiring one at a time. I'm not sure how the wiring all fits together yet, but at least I'll have the old replaced with new and I'll be able to continue tracing the electrical system. Some day I'll have it sorted.
The biggest part of the work was removing and disassembling the lamp test switch. That is, the momentary push switch to test the functionality of all the lights in the panel. Since all the lights are incandescents, this is important to ensure they are functioning. The switch is an assembly of 4 separate DPST momentary switches. The circuitry wasn't obvious until most of the old wiring was removed and I could get a close look at the switch. Cleaned and lubed the switch and got it functioning perfectly. Replaced all the wires with new with lengths and connections to match the originals.
Removed some of the fuse holders. Most of these were damaged. Fuse holders are cheap so I'll replace them. The fuse holder for the trim servo was odd in that its housing was larger than its neighbouring fuses. I'd noticed this previously and was hoping I'd figure out why. I believe I now know why. I suspect that when the plane was built, they ran out of the normal fuse holders and substituted this larger one in for the trim servo. The hole in the panel was crudely cut. It looks like someone at the factory 50 years ago used a rough round file to enlarge the hole. It is nothing like the perfectly cut out holes for all the other fuses and components.