HP 1220c series printers are generally very low maintenance. They do not require regular or periodic internal cleaning, but occasionally ink can build up and dry on cartridges and print head nozzles. If you are experiencing gaps or uneven pigment distribution on paper when you print, then most likely there is dry ink clogging your print heads. This can easily be fixed without ever opening the printer because HP 1220c printers are programmed to clean easily using the buttons on the printer.
Turn on the printer.
Press and release the "Cancel" button twice while pressing and holding down the "Power" button.
Release the "Power" button. Give the printer about one minute to moisten and dislodge the dry ink.