Ya, will try a torx bit tomorrow! I always clean out/off the rust or crud from threads before I try to remove something, don't know why this set screw is stuck in there. May apply some heat to it, but will need to take it apart as to not burn the disc, which now that you guys got me thinking about it, I should rebuild completely as the PO rebuilt it(why it was lost) and I not sure of his ability after this set screw!!