Question about Charging Light

[Bikesmith01]

Hey Friends,
After over a year of searching, my wife and I had our 911 delivered yesterday. It's a 1975 911S coupe. We're super excited, and delighted that it seems to be in even better shape than we expected.

It does have a few flaws, of course. One in particular I'd like to address right away. The alternator warning light doesn't turn off regardless of engine RPM.

First, the idiot check: Alternator warning light is the bottom light in the middle of the oil gauge, right? labeled with a G? I think I'm reading the manual correctly, but I have been known to make stupid mistakes before. Also, I'm running the engine up to about 3000 RPM to check this. That should be enough to make the light turn off, right?

So assuming there really is some issue here, rather than me just being dumb, do you have any suggestions for how to go about diagnosing this?

I'm looking at it as either A) Bad alternator B) Bad regulator C) Bad warning light. Any possibilities I'm missing?

The belt to the alternator is in great shape and well tensioned (strums when I pluck it), so I doubt that's an issue. I'm checking the Clymer book for the car and it says run the car at 3000 RPM with lights/accessories on and check the volt across the B+ and D- terminals of the alternator, looking for 13.5 to 14.5 volts. Sounds like a great place to start, but I still have a couple questions: First, how do I get at those terminals? It seems like they're buried in the blower shroud and I'd have to pull the alternator just to get at them? Am I missing something here? Second, If I do that test and get the expected voltage, would that definitively indicate that the alternator and regulator are good and that my problem is the light itself?

Thanks in advance for your help here. I realize this is a pretty basic question, and believe it or not I'm actually an okayish mechanic. I'm just feeling a little overwhelmed by having a real live Porsche sitting in my garage right now and could do with a bit of hand-holding
-Jon