DIAGNOSIS Clogged printhead nozzles. This is common if the printer sits unused for weeks. The ink dries in the microscopic nozzles.
FIX Do not run more than 2 head cleanings in a row. Instead, run the printer's 'Printhead Deep Cleaning' utility from the control panel. This uses more ink but applies stronger pressure. After, print the 'Print Quality Report' from the same menu to check for improvement.
IF THAT DIDN'T WORK You may need to manually clean the printhead contact. Power off, unplug, and remove the cartridges. Locate the printhead under the carriage. Dab a paper towel with distilled water, wring it out, and gently hold it against the nozzle plate for 60 seconds. Do not rub.
HEADS UP Excessive automated cleaning wastes ink. If manual cleaning fails, the printhead is likely permanently clogged and requires replacement. HP does not recommend soaking this printhead.