Art Questions: Tools and Techniques

Thought this might be a handy thread.

So, there's a foggy film on the inside of the glass of my husband's scanner, and it's affecting the quality of the sketches he scans. It's an easy enough problem to fix, if we could just get inside.

(I have a guess as to what might be causing it: deterioration and thereby off-gassing of a plastic component under the glass, with buildup collecting on the glass.)

Anyway, has anyone else had this trouble, or have ideas on fixing it, short of buying a new scanner?

Thanks!