Brother HL-L5100DN User Manual page 308

10. Turn the edge of the drum unit toward you while looking at the drum surface to find the mark.
• To avoid print quality problems, DO NOT touch the surface of the drum unit, only the edge.
• You can turn the drum unit gear more easily by pulling down the black levers. When you have finished
turning the gear, push the levers back to the original position.
11. Wipe the surface of the drum gently with a dry cotton swab until the mark on the surface comes off.
NOTE
DO NOT clean the surface of the photosensitive drum with a sharp object or any liquids.
12. Put the toner cartridge firmly into the drum unit until you hear it lock into place.
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