I'm shocked some have no issues and don't use locktite. I wouldn't stand a chance without locktite. But the locktite will loosen up if your pinion gets super hot. This can happen on mod1 grears if your mesh is out a bit. End of the day, two things that make the biggest difference for me is locktite on the screw and a bit on the shaft dried OVERNIGHT, and most importantly make sure your set screw isn't shiny stainless or smooth silver steel. It needs to be the black oxide finish. The smooth screws just don't grip in the threads.