It maybe possible that you have a damage Image Unit. You already did what is necessary to check for any dirty. Any way recheck:
- Remove the Imaging Unit from the printer.
- Use a clean, dry lint-free cloth to clean the top of the Imaging Unit. Wipe away any loose Toner (Dry Ink) or other debris found on the exterior of the unit.
- Re-install the Imaging Unit.
If this doesn't help you should consider place a call.
Be sure to give out Kudos and select "Accept as Solution"