Slipper adjustment ring screw size?
 

What size hex wrench is supposed to be used for the screw that locks the slipper ring? On the screw that is in mine 2mm can work, but has too much play, and 2.5mm is too large. Likewise, 5/64 has too much play, but 3/32 is too large. The screw is definitely in perfect shape, not rounded or stripped, and the tools I'm using are almost brand new, also in perfect shape.

So far the 2mm is the closest, but every time I have to tighten or loosen it I cringe because it feels like it's on the verge of stripping out. If I wanted to replace the screw what is the proper size?

The screw it's self is a 2.5x10mm and takes a 2mm wrench. Have you tried a different wrench? Hex wrenches can vary greatly in actual size.

I tried my L-shaped hex and my hex drivers. No worries though I'll replace it with a new one. Probably just a random bad screw that was slightly out of spec.