Brother HL-L3230CDW Online User's Manual page 290

7. The colour of printed dots on the Drum Dot Check Sheet is the colour of the drum you should clean. Remove
the toner cartridge and drum unit assembly that matches the colour causing the problem.
CAUTION
We recommend placing the toner cartridge and drum unit assemblies on a clean, flat surface with
disposable paper underneath it in case you accidentally spill or scatter toner.
IMPORTANT
To prevent damage to the machine from static electricity, DO NOT touch the electrodes shown in the
illustration.
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