Joe J wrote:
....

The gas company guy said it just needed tightening. I'm thinking that
actually means I need to completely disassemble this from the union
down, clean all the parts up and start over with new pipe dope and
reassemble from the heater back to the union. Or am I missing an easy fix?

Yep (and nope)...

Check on condition of the pieces, of course, before reusing.

Is the leak confirmed at a threaded joint not a pinhole failure in the
body of the tee or similar?

There is a water trap somewhere in the line I presume? Be good time to
clean it out if so, or install one if not.

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