Looking for some suggestions. The headlight vertical adjustment on my car went south (literally - headlights looking at the ground) and when I started to dig into it, I found out why. The adjusters use a plastic "driven" gear on a screw to move a slide in and out to adjust. The gear is old and deteriorating, and was loose on the screw.
This is what it should look like:

This is what it looks like:

The gear is looking kinda worse for the wear:

I thought about epoxying it back on (minus the "drive" gear), but am concerned about the plastic gear continuing to deteriorate, and am thinking I could put a spacer - nylon or aluminum - on the screw to remove any play and tack weld a nut to the back end of the screw so that I could adjust the headlights again.
My concern with the tack weld is that the screw goes into a plastic housing, and they don't like heat. I think that if I welded it and submerged it in water quickly, the plastic would be OK though.
Any input? Options I'm overlooking? New housings are $74/each, and both sides are affected with the plastic rot, and I can't afford that at the moment.