Canon imageCLASS MF266dn II User Manual page 546

When to Replace the Drum Cartridge
When a Message Appears on the Screen of the Control Panel or Remote UI
Follow the message on the screen to prepare a new drum cartridge and replace the old one. Print quality
may suffer if you continue using the drum cartridge without replacing them.
For details about the message and how to resolve it, see the following:
A Message Appears(P. 628)
When Print Quality Deteriorates
If printouts show any of the symptoms below, the drum cartridge is near the end of their lifetime. It is
recommended to replace the drum cartridge even if a message does not appear.
Streaks appear
White spots appear
Replacing Drum Cartridge
1
Lift the control panel.
If the feeder is not closed completely, you cannot raise the control panel. If you try to raise it by force, the
machine may be damaged.
2
Open the toner cover.
Maintenance
Printing is uneven
Partially faded
537
Toner smudges and splatters appear