It may simply be that the brushes in the alternator are worn down to where they no longer make good contact. The brushes are part of the regulator which is separably replaceable for about $40 and you can buy one from FastLane right here on the forum (they support this forum).

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970