Lexmark MX721 User Manual page 231

Troubleshooting
Action
Step 1
a
Check if the printer is using a genuine and supported Lexmark
toner cartridge.
Note: If the toner cartridge is not supported, then install a
supported one.
b
Print the document.
Is the printer printing solid black pages?
Step 2
a
Remove, and then insert the imaging unit.
Warning—Potential Damage: Do not expose the imaging unit
to direct light for more than 10 minutes. Extended exposure
to light may cause print quality problems.
Warning—Potential Damage: Do not touch the
photoconductor drum under the imaging unit. Doing so may
affect the quality of future print jobs.
b
Print the document.
Is the printer printing solid black pages?
Yes No
Go to step 2. The problem is
solved.
Go to step 3. The problem is
solved.
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