years ago when I was in the sign biz, we used a plastic polish that was made for that purpose. you have to use a real fine wet or dry sand paper and water, and wet sand the scratches out, I think it was like 1500 grit. If the scratches arent to deep it shouldnt take much to get them out, once thats done you hand polish the sanding marks out. just make sure you take the cover out though, cause this tends to make a mess. Not to say your dumb or anything, but youd be surprized at the people that wouldn't. Anyhow, you should be able to pick some up at your local plastic supply. if not they should be able to tell you where to get some. hope this helps.