Hi,
The fuser may need to be replaced. Please contact HP Technical support at 1-800-474-6836 to troubleshoot/isolate the issue.
Also please do ensure that when you are using the glossy media, the printer driver settings is set to the following:
1: Paper Type: Glossy
2. Paper Size: Letter -If you are using Letter size glossy media.
This is to ensure that the fuser fuses the toner properly on the media and there by reduce defects on the media.
Although I am an HP employee, I am speaking for myself and not for HP.
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