[Boatanchors] Sprague TO-6A weird dial problem

[Ken Kaplan]

This came as a surprise. My Sprague TO-6A main dial has darkened to the 
point that I can't see the markings on the main dial. The main dial 
is/was clear plastic. The markings are on the inside surface and you 
read through. The markings (scales) are still there. The only thing I 
can possibly attribute it to is a little bit of MIG welding that I did 
in the area. It wasn't close enough to reach the unit (about 6 feet 
away) and it was only about 15-20 seconds of welding. Probably lots of 
UV did it. Question is does anyone know how to reverse the darkening? 
I'm guessing it is permanent but thought I'd ask and give out a warning 
about welding anywhere near dials, plastics, etc. I'd guess that a photo 
strobe might also be cumulatively risky although they don't rise to the 
level of a welder. Anyone have a surplus main dial for the Sprague?

Ken