Welcome.
Best bet is to take some time to read through the entire thread. Will be the best way to gain the most insight from past and present owners. Never know, you may even see a reference to the same boat here.
My 96 is probably even a little slower again, although it's always difficult to compare with different weight/loads, bottom condition and water conditions!
Keen to see what decisions and results you go with.
I need to replace most of these resetable circuit breakers, but I'm struggling to find a good straight-swap replacement here is AUS. Has anyone replaced these, and if so what did you source?
I dont think it will solve all the issues you described but I think it will help part of the way. The dead battery not being a dead battery though has me thinking. Maybe check your earth strap and make sure it's good....
I've been through a lot of things with my generator. For the low cost and some of what you mentioned, grab some new capacitors and put them in. Easy job and one thing to take out of the next few troubleshooting steps.
I'd then be checking the governor oil level.
As for the not starting/dead...
In case it helps anyone else, westerbeke coil and resistor (037968) AU$580 is the same as a Daihatsu Charade, I chose an Aussie brand, Tridon TIC074 replacement for $80 and got the generator running again immediately.