HP Officejet J6480 All-in-One Printer - Manual (Page 137)

To clean the glass strip inside the automatic document feeder
1. Turn off the HP All-in-One, and unplug the power cord.
NOTE: Depending how long the HP All-in-One is unplugged, the date and
time might be erased. You might need to reset the date and time later, when
you plug the power cord back in.
2. Raise the lid, as if you were loading an original on the glass.
3. Lift the cover of the automatic document feeder.
Clean the device 133