46erjoe writes:

I think I need to find a website with helpful info on sweating copper.
I learned by trial and error and I probably need to UNleard some
things. I also learned that different fluxes go with different kinds
of solder. I thought they were all the same! Hey lead is lead, right?
Wrong.

Well, there's no lead in plumbing solder any more. It's now almost all
tin, with a little bit of antimony or something else (but definitely not
lead).

Having said that, I've always had good results using decades-old acid
paste flux with the new lead-free solder as long as the surfaces being
soldered are clean.

It would be useful to know *why* you got that pinhole leak (yeah, I
know, probably too late now). If you just didn't get it hot enough or
apply enough solder to get sucked into the joint, but it's otherwise
clean and adequately fluxed, reheating might work. But if it's dirty
inside the joint, no amount of reheating is likely to help.

Dave