HP LaserJet M9040M9050 Multifunction Printer series - Manual (Page 187)

2. Locate the top and bottom ADF glass strips.
Figure 11-9 Clean the ADF delivery system (2 of 5)
3. Clean the glass strips by wiping them gently with a clean, damp, lint-free cloth.
4. Locate the white, vinyl backing.
Figure 11-10 Clean the ADF delivery system (3 of 5)
5. Locate the white, vinyl calibration strips.
Figure 11-11 Clean the ADF delivery system (4 of 5)
6. Clean the ADF backing and the calibration strips by wiping them with a clean, damp, lint-free cloth.
7. Close the top cover.
Figure 11-12 Clean the ADF delivery system (5 of 5)
Clean the top ADF glass strip
If you are still experiencing poor copy quality, you might need to clean the top ADF glass strip.
ENWW Clean the MFP 173