HP LaserJet 9000 Printer series - Manual (Page 89)

6 Product maintenance 89
Cleaning the product
Cleaning the scanner glass
z Clean the scanner glass only if dir t is visible, or if you see poor copy quality (such as streaking).
z Clean the scanner glass surface by wiping it gently with a clean, damp, lint-free cloth. Use an ammonia-based surface
cleaner to dampen the cloth.
CAUTION Do not pour or spray liquids directly onto the scanner glass.
CAUTION Do not press hard on the scanner glass surface. You might break the scanner glass.