A single sheet of media might be defective.
Try reprinting the job.
The media's moisture content is uneven or
the media has moist spots on its surface.
Try printing with new media. See
for more information.
The media lot is bad. The manufacturing
processes can cause some areas to reject
toner. Try a different type or brand of media.
The print cartridge might be defective. See
Changing the print cartridge
If these steps do not correct the problem, contact an HP-authorized dealer or service