I'd seen this thread when it opened. The point of failure is where a retainer is staked to some pot metal to hold the tensioning coil spring in place, right?
Haven't had a chance to try and fix one, but I was thinking... Find a piece of threaded steel tubing, like the kind used in the centers of lamps/lighting fixtures. Or maybe a pipe nipple. Remove the wiring. Drill the broken area out if needed, and epoxy the tubing/nipple in place, leaving enough thread length to use a matching nut to compress the thing back together. Dab of LocTite and tighten the nut till the tension's back on the spring. Leave the length for future adjustments or cut flush to preserve looks. Reinstall wiring.
Could use threaded rod if no wiring or willing to run wiring externally. Somebody mentioned Velvac uses a hydraulic press to assemble the spring and retainer. My idea of using something threaded eliminates that need.
This is just a mental exercise based on the words I've read and the pix I've seen. To me, if it works, a repair using steel is better than new and a very expensive part is restored.
I used to be jealous of those mirrors. Now I'm happy to have what we've got, the Rental Truck kind:
The round mirrors are cheap chain auto parts store ones with home made aluminum brackets.
Truck stops have much nice versions of both. So does Amazon.
