Brother MFC-9840CDW User Manual page 197

Note
When you put the drum unit in the
machine, match the green guides (1) of
the drum unit handle to the green
arrows (2) on both sides of the machine.
2
1
Troubleshooting and routine maintenance
h
2
1
i
2
Push the drum unit in until it stops.
Close the front cover of the machine.
When you replace the belt unit with a
new one, you need to reset the belt unit
counter by completing the following
steps:
Turn on the machine's power switch.
C
185