Brother HL-6050DN - Manual (Page 121)

5 - 6 ROUTINE MAINTENANCE
Caution
Put the toner cartridge in the drum unit immediately after you have removed the protective cover.
To prevent degradation to the print quality, do not touch the shaded parts shown in Figure 5-7.
Figure 5-7
6
Put the new toner cartridge firmly into the drum unit until you hear it lock into place. If you put it in
properly, the lock lever will lift automatically.
Figure 5-8
Caution
Make sure you insert the toner cartridge properly or it may separate from the drum unit.
7
Gently wipe the scanner window with a dry, soft cloth.
Figure 5-9