Possibly has dried ink and needs to be cleaned.
Some printers have a printhead cleaning procedure.
| To clean the printhead on an HP printer, access the printer settings through the HP Smart app, navigate to "Print Quality Tools," and select "Clean Printhead"; this will initiate a cleaning cycle where the printer will automatically run a cleaning process to clear any clogs in the printhead |
This link shows cleaning the 8600 printhead and removal is shown here.
This is another type of printhead cleaning, different from the above.
Cleaning and removing ink is shown below by our "Scullery" team.
An HP original video on how to clean the printheads by our experts. Yes, this can get messy, but it works. If your ink levels are good but you are printing blank pages then this is likely the solution.
Official HP advice on cleaning.
let me know which of these worked, if any.