Having just tightened the teeny screws that hold the joints in place for the first time since I glued it to the helmet, I’d say it’s working fine. The 2-56 elevation setscrew has worn a slight dent in the arc and the 3-48 azimuth screw worked slightly loose; the mirror didn’t fall apart, but the position wasn’t as stable as it should be.
If I ever re-do the design, I’ll try adding a recessed metal (brass?) strip along the top of that arc, as that’s the most finicky adjustment. Perhaps a shoe under the setscrew would be better?
Two years of road grit show up clearly against the yellow plastic, though:
For the record, those 2-56 setscrews require 35 mil hex keys; as Eks reminds me, any design requiring those screws is just crazy talk.