That headlight will most likely need to come apart for repair (would be much easier, anyway).
There's a seller on ebay that always has parts bundles for Lits.
http://www.ebay.com/itm/271552593304
They always have a lot of parts. Just be sure you get the correct parts as there are at least 2 types of Lits that I'm aware of.
I recommend Meguiars Plast-X with a foam polisher to remove mild discoloration. It's an easy, one-step solution.
Scratches or heavy oxidation will require wet sanding, polish and new UV coat for future protection.
Threaded Mode
