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How to replace the Drum Unit of Brother MFC-9840CDW Multifunction Printer

  1. Turn off the power of your Brother MFC-9840CDW Multifunction Printer, and then open the front cover by pushing down its lock release button.
  2. Grab the green handle of the exhausted drum unit and pull upwards, and then pull the exhausted drum unit towards you until it stops.
  3. Unlock the exhausted drum unit by releasing the gray lock lever on the left side of the printer, and then take the exhausted drum unit out of the printer. Please note that you must avoid touching the components surrounding the installed drum unit, the photoconductive drums of the new drum unit, and the contact areas of the toner cartridges.
  4. Detach all toner cartridges from the exhausted drum unit by grabbing each cartridge's handle and pulling upwards.
  5. Take the new drum unit out of the transport packaging, and then remove its protective plastic cover.
  6. Insert all of the previously removed toner cartridges into the new drum unit by following this order (front side of the new drum unit-rear side): Black (K), Yellow (Y), Magenta (M), and Cyan (C).
  7. Make sure that the toner cartridges' handles are folded down and that the gray lock release lever is still in ''upper''/''unlocked'' position, and then insert the drum unit into the printer slot until it stops.
  8. Push the gray lock release lever down, and then slide the new drum unit into the slot until it stops.
  9. Push the new drum unit down to lock it into the slot, and then reset the drum counter by executing the procedure included below.
  10. Close the front cover and turn on the printer.
  11. Navigate to the [84. Reset Menu] by pressing [Menu] – [8] – [4].
  12. Use [^] or [v] to choose [DRUM].
  13. Press [OK], and then press [1].
  14. Finalize the drum counter reset procedure by pressing the [Stop/Exit] button.