HP Color LaserJet 8550 Multifunction Printer series - Manual (Page 126)

EN Replacing Printer Consumables 125
Note The color toner carousel will not rotate unless the clear door is
closed, the imaging drum and black toner cartridge are installed
(including removing the orange seal from the black toner cartridge
and swinging the upper lever to the left), and the upper right door is
closed.
Frequency for Replacing Printer
Consumables
The following table lists the approximate schedule for replacing
consumables and the printer messages that appear when each of the
consumables should be replaced. Part numbers for each consumable
can be found in “
Accessories, Options, and Related Products ” in
chapter 8 . For best print quality output, use HP consumables that
have been designed to work together in this printer.
Note Do not shake the toner cartridge in attempts to extend the cartridge
life. For more information on replacing the toner cartridge, see the
installation guide included with the toner cartridge.