Yep, this particular one had a set screw that was stripped. The set screw also had it's top split in half so the screw driver wouldn't even work anymore. We are talking a #4 machine screw, pretty small to work with!
Anyway, I carefully screwed the set screw out using a tiny pick. I then drilled the hole out (remember the threads were all messed up) to for a #6 tap. I tapped out the threads and installed a new allen head set screw.