Dell 3010cn Color Laser Printer - Manual (Page 121)

7. If replacing just one toner cartridge, close the front door and you are finished.
8. Repeat steps 1 through 4 when inserting the remaining cartridges.
Basic toner cleaning instructions
A cleaning rod for cleaning inside the printer is installed on your printer.
1. Open the front door.
2. Pull out the slide bar that is inside the printer on the right side until it stops.
The access window cover slides open.
CAUTION: If you find it difficult to push down the handhold, remove the cartridge and insert the cartridge again.
NOTE: Make sure the toner cartridge is installed correctly. Otherwise, the front door cannot close firmly.