Brother MFC-J491DW Online User's Manual page 535

IMPORTANT
DO NOT touch the print head. Touching the print head may cause permanent damage and may void the print
head's warranty.
When a print head nozzle is clogged, the printed sample looks like this.
After the print head nozzle is cleaned, the lines are gone.
Related Information
• Check Your Brother Machine
• Paper Handling and Printing Problems
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