Testing alternator, charging system light is on?

Thanks for the quick response, Ken! I already watched that video - very helpful. I've attached a couple images - hope they're useful. I don't want to risk doing any damage to the supercharger or engine. I think they built the entire car from the alternator out. ;-)

Just realized I never followed up with you on this one. The problem just went away one day. I still think that the voltage regulator is wonky, though. Since I can't access the post to run a test on it, I'm stuck with it for now. I was able to get the wiring harness open and gave contacts a good cleaning. It needs a new serpentine belt, for sure.

I have an update on the alternator issue, and a follow-up question for you. I found a post on a forum that said the Millies tend to have an issue where the alternator gets "gummed up, " and stops charging the battery. The recommended fix was spraying it down with WD-40 and giving it a few taps to shake the buildup loose. I tried that, and it worked! My question is: Is there any way to ensure that the alternator won't just crap out again while I'm driving, or is it time to replace the alternator to play it safe? Pretty pricey job, because it's a nightmare to access the thing on this car.

Thanks, Ken. Hard to believe the brushes could be worn out on a car with under 30K miles (yep, you read that right), but I guess maybe it's just old age and corrosion.

Yeah, the car was my "weekend toy, " back when I had enough money to do that. The alternator is a crapshoot, unfortunately. It's too buried to yank out and have bench-tested, so there's no way to tell if it'll fail again while I'm driving. The guy who designed that engine compartment was a sadist!