The LCD screen on the Brother MFC-9125CN will alert the user with a variety of warning messages regarding its consumables. A TONER LOW / PREPARE NEW <COLOR> TONER CARTRIDGE message will appear when one of the four color toner cartridges is running low. When this message appears, it is time to order a new toner cartridge so that it arrives before the cartridge completely runs out.

NOTE: The word <COLOR> will be replaced by CYAN, MAGENTA, YELLOW or BLACK.

When a cartridge has run completely out of ink, the unit will display a REPLACE TONER message, at which point the cartridge is no longer usable. The cartridges must be replaced with the device power turned off.

Lift the handle on the front cover of the printer and the four toner cartridges will all be accessible. Choose the color that was shown on the LCD screen and remove the drum/toner cartridge assembly. The cartridge must be separated from the drum by pressing down on the GREEN release lever. The old toner cartridge can be discarded.

Take the new cartridge of the correct color out of its packaging and shake it long ways a few times to loosen up the toner inside, the pull off the protective cover. Press the new cartridge into the drum unit until it snaps into place, then slide the drum/ toner combo back into the machine in the correct spot. If an additional cartridge needs to be replaced, repeat this process.

When finished, close the cover of the unit and restore its power.