Brother MFC-9440CN User Manual page 168

To avoid print quality problems, DO NOT
touch the shaded parts shown in the
illustrations.
152
f
Turn the drum unit over by holding the
green handles. Make sure that the drum
unit gears (1) are on the left hand side.
1
g
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 the find the exact position of
the poor print.