Long. Printers are pretty complicated machines, because they have to work with a natural product that shrinks, expands, folds, rolls itself up and sticks to other pieces of paper. I once heard a printer engineer explain that they use small puffs of air to lift the paper, but because there’s also heat involved in the printing process that the paper sometimes rolls itself up or expands which causes jams etc. And I’m sure there’s more going on.
Which isn’t to say that HP aren’t bastards.
Like others have said, usually there’s a bolt on the underside, but I have trouble seeing it in this picture. In some faucets (also some Grohe) there’s an Allen inside the faucet. Remove the spout by loosening the ring around the spout and there should be a threaded rod in which fits an Allen key.