I have an intermittent generator light problem. Has not occurred at startup until today. Sometimes it doesn't occur at all. When it does occur generally the car will have been warmed up and running for at least 20 minutes before the light comes on. After awhile, 10 minutes, longer sometimes, it goes off. Today after 1/2 hour drive, I shut it off - was at a friend's for 40 minutes, and when I tried to start it - click, then key off and on and it started, but the gen light stayed on. After driving for 10 minutes, it went out.
I have checked grounds (body to engine and body to battery). I pulled the previous generator and checked the brushes, which appeared good. Lightly dressed commutator with fine emory cloth.

When this same issue perrsisted 6 months ago, With a friend's spare I was able to replace the generator and the same symptoms continue to occur, although erratically even though the brushes and commutator both look good in this one as well.

Seems like an intermittent connection - where?

I don't know why, but having the GEN light come on, is extremely disconcerting, especially on a 300 mile road trip.

thanks