Brother 8060P MFC-9060 Owner's Manual page 165

T R O U B L E S H O O T I N G A N D M A I N T E N A N C E
5
Gently rock the toner cartridge from side to side five or six times.
6
Slide the new toner cartridge into the opening on the right side of the
drum unit. To ensure that the toner cartridge and the drum unit fit
together correctly, make sure that the toner cartridge guide bar is
exactly aligned with the guide slot in the drum unit.
Drum Unit
7
Gently turn the lever on the toner cartridge backward until it stops.
Toner Cartridge
155