HP Color LaserJet CM4730 Multifunction Printer series - Manual (Page 285)

Vertical lines
Defect description
Vertical lines appear on the page.
Possible causes
The device needs to be cleaned. Operating environment or media in use does not meet HP
specifications.
Troubleshooting and suggestions
1. Make sure that the environmental specifications for the device are being met.
2. Print the Print Quality Troubleshooting Pages and follow the diagnostic procedure listed on the first
page to help isolate the defect to a particular component.
ENWW Correct print quality and copy quality problems 269