abalto, I had a similar problem with my Benz, flickering lights. Yes, it was the voltage regulator but that was discovered after the battery light started glowing at idle. It's an easy fix, DISCONNECT THE BATTERY "+" for safety, raise the front of the car (my "large frame" won't fit), take off the belly pan and there was the alternator with more than enough room to get to it. Two screws and it'll fall into your hands, new one screwed in, you'll have to hold it in place, and you're almost done. Total time to replace mine, not counting the smoke break, 30 minutes, includes raising the car and dis/reconnecting battery.

On the old one, one brush worn even with the main body, the other brush has 1/4 inch remaining, yup, worn out. Why can't other cars be so simple and easy to work on??

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1991 300SE (my ride, 279,000 miles, looks almost new
1954 Cadillac (21 yo son's car, he bought when age 15)
1972 SeaBird 19 ft runabout (old but solid, slant six, Volvo sterndrive perfect condition, undergoing complete overhaul and refit)
1998 Toyota Rav4 (my sons daily driver when he is in the Continental US, PROUDLY serving in US Navy)