I tried the rubber band trick, no go and I don't have the tools to cut a slot in a screw. Then I remembered my snap back watch case tool, it's like a spring loaded blade to pop off tightly fit snap on watch backs. It made quick work removing the screw, destroying what little of it was left. I've never seen a screw torqued down this hard, yet the other side came off like they usually do, with a quick wrist turn to crack the initial resistance of the Loctite.
Now I need a new screw, but at least I could switch the clip over to left hand carry. Thanks for all your help everyone. :thumbup: