So I think this is likely a long shot, but I thought I'd give it a try anyway. I bought a headlight from an ebay seller and because of poor packaging the vertical center adjustment screw was snapped off. Gluing it back together just on the broken surface ends will not be strong enough, and of course no glue can get on the threads. I am considering a possible fix of drilling down the center of each piece maybe 3/8", and inserting a cut off piece of a stainless steel screw with epoxy to bridge the break and give it some strength.

Before going through that effort I'm checking here if anyone has a broken headlight that would be willing to part with this screw. The screw fits into a split nylon bracket inside the headlight. There is no need to take apart the headlight to remove it. There is enough give in the attaching bracket inside that when unscrewing the screw the little balled end will just pop out of the bracket while unscrewing it from the case.