Dropouts, Vertical lines, Gray background – HP Laserjet p1606dn User Manual
Page 109: Dropouts vertical lines gray background
A single sheet of media might be defective. Try reprinting
The media moisture content is uneven or the media has
moist spots on its surface. Try printing with new media.
The media lot is bad. The manufacturing processes can
cause some areas to reject toner. Try a different type or
brand of media.
Place the product in quiet mode, and send the print job
The print cartridge might be defective. Install a new
genuine HP print cartridge.
The photosensitive drum inside the print cartridge has
probably been scratched. Install a new genuine HP print
Change the media to a lighter basis weight.
Check the product's environment. Very dry (low humidity)
conditions can increase the amount of background
The density setting might be too high. Adjust the density
Install a new genuine HP print cartridge.
Solve image-quality problems