Bert Byfield wrote:
But my primary leak right now is where a water pipe has been
touching the conduit for the main house power for fifty years or
so, and the contact has caused a pinhole leak, of 5 or 6 gallons
a day. I'm looking at inserting a "universal pipe repair clamp"
between the pipe and the conduit, before I think about replacing
sections of pipe.

All you need is a slip over coupling (one w/o the ridge in the
middle) expressly for the purpose.
Cut the pipe at the location of the pinhole, clean the ends
(remember to also ream the inside of the cut to get rid of burs),
then slip the fitting over, flux and solder. Done.
Then, as somebody else noted, fix the contact point so the two
don't touch in some fashion and it'll probably outlast you.

I had never before understood why some of the couplings had ridges and
some did not. But also this pipe is only half an inch from the ceiling
so I can't get a regular pipe cutter to roll around it, and would have
to use that saw like a hacksaw blade with a handle at only one end.
I've had trouble doing this before, because the soft copper bends a bit
and is then hard to fit to the coupling. Is there a better way to cut
this pipe, or do I just have to go slowly and ream out the result?