A few scratches on the screen or some dust on the mirror doesn't mean a thing. Neither condition will affect the image quality, so I suggest leaving well enough alone if all else is working properly. The mirror is a first surface mirror, meaning that the reflective surface is on top of the glass support as opposed to most common mirror which have the reflective surface below the glass. These surfaces are VERY delicate and scratch very easily. They can be cleaned, but the procedure is risky if you don't know what you're doing. I wouldn't do any more than blow any loose dust off with a blower. Don't even use canned air.