NDD, you forgot the #1 SF Prime Directive.
NOTHING DIFFICULT IS EVER EASY !!!
Clean both the screw and the handle with a good de-greaser, Alcohol will work. Then get some Clear Fingernail Polish and dip the threads of the screw into it and put it back together!! (Let dry!)
Simple as that. Then PM me with your addy and I'll launch some Loctite in your direction !! COORDINATES REQUIRED !!
Later
Martin