Carl, was there any visible fatigue, cracks or deformations in the brass (body or tube)?

I found more images of these leaks and the failure point was always at the soldered union between the gauge body (hard brass) and the bourdon tube (soft brass).

If the fatigue was localized to the solder, which you replaced, doesn’t track that this wouldn’t be as good as original.

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1981 240D 4sp manual. Ivory White.