Brother MFC8420 Service Manual page 182

(3) Push down the blue lock lever and take
the toner cartridge out of the drum unit
assembly.
(4) Unpack the new toner cartridge. Hold
the cartridge level with both hands and
gently rock it from side to side five or six
times to spread the toner evenly inside
the cartridge.
(5) Remove the protective cover.
(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. Make sure
you fit the toner cartridge properly or it
may separate from the drum unit.
(7) Clean the primary corona wire inside the drum unit by gently sliding the blue tab from
right to left several times. Return the tab to the home position before you put the drum
unit back in the machine. If you do not, printed pages may have a vertical stripe.
Home position
(8) Put the drum unit assembly back in the machine. Close the front cover of the machine.
MFC-8420/8820D/8820DN, DCP-8020/8025D/8025DN
Fig. 5-11
5-5
SERVICE MANUAL
Fig. 5-8
Fig. 5-9
Fig. 5-10