A screws in one of Mary’s eyeglasses unscrewed itself, but, miraculously, we found it and I retired to the shop.
Because the glasses have spring temples, the screw would not align no matter what force I applied to it:
So I just embiggened the hole until the available force did the trick:
Dots of Loctite worked into the threads should prevent that from happening again, but I’ve learned to never say never.
In retrospect, the temple pivots have an exposed slot that I think would allow jamming a block in place after pulling the spring-loaded pivot outward. Temple springs are impossibly stiff and I have previously failed to budge them in glasses without the slots, so I don’t know how well that might work.
Verily: If brute force isn’t working for you, then you’re not using enough of it.
The Smell of Molten Projects in the Morning 
Doesn’t that make that side too floppy? How do they extend the spring to put those screws in at the factory?
We decided slighly loose was better than completely missing … [grin]
I’d like to think there’s a fixture involved, but it may be as simple as: