HP Color LaserJet 8550 Multifunction Printer series - Manual (Page 200)

EN Print Quality Problems 199
To clean the transfer drum
1 Leave the printer powered on and
open the printer’s front door.
2 Push the white button on the lower
(green) lever and swing the lever to
the right.
3 Open the upper door on the right side
of the printer.
4 Using the handles, gently pull out the
transfer drum until it stops.