headlight with rotary zoom and rotary head

http://www.ebay.com/itm/121043687402?ru=http%3A%2F%2Fwww.ebay.com%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D121043687402%26_rdc%3D1

I´ve bought this one but there are two problems with it, the first thing is that i can see fingerprints and a hair inside the lens.
Second problem is that the screw is only drilled to alu from flahlight and not fixed with a mother., so I need to open the whole flashlight and I don´t know how I will work.
I hope you can tell me what I need to do.