Mike Berger wrote:

I'd go for a binary chop and insert a few ball valves in the line
to isolate parts of the system. ...

Well, it's not plumbed into a distribution system. This JUST the
compressor that's leaking. But I am chopping its parts. In stages I've
removed: the pressure guage, the drain plumbing, the quick release
outlet, and the pressure switch. In each case, I plugged their port and
soap checked it. Still leaking! I only have the pressure relief
valve and the Christmas tree itself to go. And the tank itself. Bob