Not sure about the 660C but just worked an 825C that it seemed like the
cartridges were bad based on the self diagnostic and test page (see the
HP site on how to run these). So I tried to replace the ink cartridge
with a generic that works in my 827Cse and listed as working for the
800 series but got that flashing yellow light.
I Freecycled this and the guy I gave it to said it worked fine after he
put in new OEM cartridges.
Richard