If I remember correctly HP used cartridges with an integrated printhead and water-based ink. There is probably still ink in the cartridge, but the print head nozzles are clogged with dried ink. As the ink is water-based, it will easily dissolve in water. Heat a pot of water just below its boiling point and submerge the printhead of the cartridge for a few minutes or until ink starts to flow freely (like a nib pen) when the printhead is wiped with paper towel. A few "head cleaning" cycles in the printer will exercise the nozzles further and help to remove the last few clogs. Doing that between 2-minute soaks in hot water seems to work best. I've done my own printer service (and other's printers) for a few years, this is from experience B) Epsons and other printers with separate (not easily replaceable) printheads are cleaned in much the same manner, although with their alcohol-based inks an overnight soak in ethanol works much better to clear clogs. To lessen the chance of plugged printheads in the future, you can use diluted ink which is thinner and less likely to dry out and become viscous (it's also cheaper than using 100% ink ). Black can usually be diluted to 10% by volume with no quality loss, beyond that it becomes dark grey but still legible... (good for draft printing or high-volume low-quality) as for the colors, only the cyan and magenta can be diluted quite a bit, the yellow is already faint so 50% is probably as low as I'd go without noticeable color loss.