When you replace the voltage regulator, keep the old one for a couple of days. If the problem is confirmed, then toss the old VR. If the new VR does not fix the problem, the old one is good, so put it away in the trunk with your tools and spare tire. A known good spare VR is a mighty nice thing to have if you ever have a failure on the road.

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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