danglerb

Electronic contact cleaner sounds like a good option, so does taking it apart for a full checkup and new brushes, dress the armature etc.

Rob Edwards

This is about as far as I got on my GTS alternator, chickened out at the thought of trying to solder/desolder the slip rings. They look bad enough to me to R&R, eventually I'll get around to it.

For cleaning I used this Gunk NM1 Electric motor contact cleaner-very satisfying, the alternator is 1/4 lb lighter for all the schmutz that was flushed out...