I replaced a friends bathroom sink tailpiece yesterday and I am having problems with a leak in the pipe with fine threads that goes into the main body of the tailpipe. It is part RP 6128 in the pic below.
When I first installed the tailpiece, it leaked. So I removed it and used teflon tape, still leaked. Then I used Rectorseal teflon pipe seal, still leaked.
So I thought maybe I have a defective pipe. So I got a new one,put it in, same thing, still leaks. Any ideas? I'm ready to put 5 minute Epoxy on this thing if i can't stop this leak.