After the hinge repair described there, those old sunglasses have been working fine and I use them regularly. The screw recently worked its Loctite loose and was held in largely by blind faith.
It’s obvious why:
A tiny dab of JB KWIK should solve that problem for the foreseeable future:
In the highly unlikely event I must remove that screw, I’ll just refer to this picture and mill the epoxy out.
The Smell of Molten Projects in the Morning 