1981 242 non-turbo: Problem is glimmering alternator light. Problem started after installing new (used) wiring harness. I accidentally had the fat red alternator cable connected to the alternator case without the insulating washer (grounded) When I tried to hook up the battery negative cable, sparks flew. I insulated the fat red cable from the alternator case, and I've been running the car for several months since then. Only obvious symptoms are the slightly glowing alt light (visible at night only), which glows brighter with each blink of the blinkers, or when high beams are on.

Things tried so far: known good battery tried, alternator to block ground redone, all the grounds over by the ww washer tank redone, checked and twisted all fuses. New brushes and bearings installed in the alternator.

Recent test results:

17.7 volts full field alternator test.
12.5 volts across battery with key out.

13.5 volts across battery at idle, not loaded.
12.1 volts across battery at idle, loaded.

13.5 volts across battery at 2500 rpm's unloaded.
12.8 volts across battery at 2500 rpm's loaded.

"Load" was high beams on, fan on full blast, AC on.

I'm not good at auto-electric, but I'm guessing maybe I damaged the voltage regulator which is mounted over by the passenger headlight on this car. Does anybody have any ideas to try, or should replacing the voltage regulator be next?
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Thanks to everyone for the help, Doug C. 81 242 Brick Off Blocks, stock, M46; 86 244, 140k , auto.