There are several things you can try to fix headlight lenses that have become cloudy, yellowed or scratched. Click on the method to find the referring poster:
Robert Thompson had this to say regarding his headlight polishing experience (edited):
"Cataract Surgery on a 1993 TSi
- 1500 wet
- 2000 wet
- Mothers Mag & Alum polish ($8.49 CT) ( this contains Kerosene, no wonder it "works" on plastic )
- Mothers Stage 1 Cleaner (wax kit) ( also contains Kerosene )
- Mothers Stage 2 Sealer
- Mothers Stage 3 Wax
- Buffed, more Buffing, still more.
Had to repeat this 3 times!
The results? Well, to start, my lens looked like they had been sand blasted. Millions of little craters that had blended and smoothed into a dull crappy looking plastic lens. You really could not look into the light and see a bulb. (I was amazed as just how crappy they were when I sat down and really looked at them)
What made this job a lot easier to do was I have a Black & Decker "Mouse". So I just strapped on the appropriate adapter and buzzed away....
Speaking of the Dremel, DO NOT use it for this project. You can't get it to turn slow enough and in a nano second you will "burn" the lens. (Gee, how would I know? Well... It takes about 30 min to sand out the burn.)"
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Replacement headlights are available on eBay. Just replace them.