HP OfficeJet 7000 (E809a) wide-format (A3, ledger, tabloid, 297x420 mm,
11.7x16.5 in), 4-colors.Utility on the computer wouldn't print but instead it reported problems with the cartridge. The cartridge was recent (certainly not empty) original HP.
I presumed it was contacts between the head carriage/cartridge holder and the cartridge. I cleaned both the pins in the carriage and contacts on the cartridge with Q-tip--no joy. I then took pencil eraser to those pins & contacts--no joy. If I had an ink eraser handy I would try that next. But the next for me is a fiberglass burnishing pencil used for cleaning up corrosion on PC boards:
GENTLY brushed each pin and contact (this is a coarse brush and removes lots of gold if you're not careful), cleaned with Q-tip and alcohol, and reinserted the cartridge.
Problem solved.