Thanks all. The Park site is very good. However, I need to back up a bit: How do I get the damn derailleur off the frame? Turning the Allen head on mounting pivot just rotates it in the frame, it doesn't go in or out. I thought it would screw out. Does it have a normal RH thread? Could there be a flat nut that's fallen off from the inside and the pivot is being held in by grit? I don't want to force it and strip the threads.