Dell 3000cn Color Laser Printer - Manual (Page 34)

7. The toner cartridge carrier rotates to the next empty slot. When the color of the newly inserted cartridge appears on
the display, followed by the Insert message, insert the next toner cartridge.
8. Repeat steps 1 through 7 when inserting the remaining cartridges.
Installing the Drum Cartridge
1. When the Insert Drum or Insert Drum Cart message appears, open the front door, then lift and push back the top
cover.
2. Remove the protective sheet from the drum cartridge.