To replace the Brother MFC 9130CW toner cartridge, first, you need to get a new one from the Brother printer manufacturer site or a trusted retail store. Make sure to turn off your Brother MFC 9130CW printer during the toner replacement. Unplug all the cables from the Brother printer and unlock the top cover of the printer. First, take the drum unit from the printer and then remove the defective cartridge. Now, unpack the new toner cartridge and shake it before you insert it into the printer. Fix the new toner cartridge in the printer. After that, insert the drum unit and close the opened top cover of the Brother printer. Now the toner cartridge of your Brother printer is replaced successfully.