Brother HL-2140 - Manual (Page 77)

Routine Maintenance
69
5
Replacing the drum unit
5
CAUTION
While removing the drum unit, handle it carefully because it may contain toner.
Every time you replace the drum unit, clean the inside of the printer. See Cleaning on page 73.
When you replace the drum unit with a new one, you need to reset the drum counter by completing the
following steps:
a
Make sure that the printer is turned on and the Drum LED is blinking. Open the front cover.
b Press and hold down the white Go button for about 4 seconds until all the LEDs light up. Once all four
LEDs are lit, release the Go button.
Improper Setup
Do not reset the drum counter when you only replace the toner cartridge.