cbushnell,
I wish that I could tell you that I have it all under control and have fugured it out- unfortunately that is not the case. I sidelined my bonny mid summer to work on the house - Fortunately I had another car that I could drive. I was planning on getting back into it very soon however since the weather is turning cold quick. I have really wanted to check out the starter solenoid for some time. I dont have the schematic but am relatively sure it picks up with the ignition switch. You are lucky that your problem is always broken. If you check your positive power rail - you should see voltage lower than 9vdc. If you start disconnecting one thing after another eventually you should come to the offending ckt. Your battery could be shorting out also. - Take it to the zone and get a load test done on it. It sounds like your alternator is sound - but your battery is still in question (lso turn your lights on and see if your battery will support that.
Please let us know if you get an answer - I plan on starting to work on mine again in two weeks.
God Bless!
cscottyr