Brother HL-4040CN, HL-4050CDN, HL-4070CDW Service Manual page 68

Note:
If you have print quality problems, clean the drum unit as follows:
(1) Pull the drum unit out of the machine and take all the toner cartridges out of the drum unit.
(2) Turn the drum unit over by holding the handle. Make sure that the drum unit gears "1" are
on the left hand.
Caution
We recommend that you place the drum unit on a clean, flat surface with a piece of disposable
paper underneath it in case you accidentally spill or scatter toner.
(3) See the print sample to identify the color causing the problem. The color of the spots is
the color of the drum you should clean. For example, if the spots are cyan, you should
clean the drum for cyan. Put the print sample in front of the drum, and find the exact
position of the poor print.
"1"
Fig. 1-6
Fig. 1-7
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