Hi all - A few days ago I noticed my bathroom sink was clogged. I disassembled the entire piping all the way to the nipple. There was lots of black gunk all the way through - I cleaned that out. However, when I got to the elbow that connected to the nipple, I couldn't find a way to get that off other than to clamp its open mouth with my wrench and just turn it counter clockwise. That got the elbow off the nipple, but it took some of the nipple's threads with it too. You'll see from the photos (hopefully) that the threads on the nipple are rusty. The black gunk continues into the nipple and I've been told I need a plumber's snake to clear the rest of it out. Also, some maintenance folks came in to look at it and mentioned something about the nipple having to be replaced (because it was old, or something of the sort). I am not sure if I need to do that or not. Any suggestions on unclogging the nipple? Or whether or not it needs replacement? And what can I do to fix the broken thread problem? Thank you in advance.