• The compatible cartridge has been installed correctly, but the printer is not registering it as installed or states it is not compatible.
• Remove the affected cartridge or cartridges from the printer.
• Turn the printer off and wait for 2 minutes.
• Turn the printer back on and wait for a further 2 minutes.
• Once the printer warns that certain cartridge or cartridges are missing, reinstall them one at a time.

• If the print quality is poor, remove the toner cartridge from the printer and gently rock the cartridge from side to side.
• This movement helps distribute the toner evenly within the cartridge.
• After rocking the cartridge 5–6 times, re-insert the cartridge into the printer and print a test page.
• If the issue persists, check the life of the maintenance items in your machine in case any of them need to be replaced.

• Print 15–20 pages and see if the problem persists.

Printouts have streaks appearing down the page.

• Remove the toner cartridge from the printer and gently rock the cartridge from side to side.
• This movement helps distribute the toner evenly within the cartridge.
• Carefully clean the drum roller to remove any excess toner.
• Re-insert the cartridge into the printer and print a test page.
• If the problem persists, repeat the previous steps.

The 40X8421-REM contains the following:

• 1 x Fuser unit
• 1 x Transfer roller
• 3 x Seperation rollers
• 3 x Pickup/ Media rollers

The image below shows which item is which:

• 1. Open the rear door of the printer and slide it off the hinges to remove it.
• 2. Press the two side latches to gain access to the fuser unit
• 3. Unscrew the two fuser thumb screws
• 4. Pull out the old fuser, install the new fuser and tighten two fuser thumb screws
• 5. Close the fuser access door, reattach and close the rear door.

Do not touch the black surface of the new roller. Oils from your skin will degrade print quality.

• 1. Open the printer’s front door and the control panel cover.
• 2. Remove the waste toner bottle and the imaging unit.
• 3. Use the gear on the right of the transfer roller to gently pull the right side up, then slide the whole roller to the right to release it.
• 4. Unpack the new transfer roller, but keep the protective sleeve on the foam for now.
• 5. Insert the left side into the arm first, then the right. You’ll hear a click when it’s locked.
• 6. Gently pull the protective sleeve off the roller.
• 7. Put the imaging unit and toner back in, then close all covers.

Avoid touching the rubber roller surface to prevent future paper jams.

• 1. Pull the paper tray out until it stops, lift it slightly, and remove it completely.
• 2. Flip down the front duplex flap to see the roller assembly.
• 3. Squeeze the latches on both sides and slide the assembly to the right to pull it out.
• 4. Hold the small paper flag down and out of the way while inserting the new unit. If it gets trapped or snapped, the printer won’t function correctly.
• 5. Slide the new assembly in until it locks and reinstall the paper tray.

• 1. Pull the paper tray entirely out of the machine.
• 2. Press the release button on the tray to pop the old roller assembly out.
• 3. Insert the right side of the new assembly first, then insert the left side down until you hear a click.
• 4. Slide the tray back into the printer.