As to get HP to react, no one I know has that answer. I checked the printer price and it appears to be worth doing the repair.
We have an HP T120, have only ever used HP ink cartridges in it, and one of them has leaked recently and caused a fault with the print head. HP technical dept. are aware that this can happen ("it happens all the time" !), but will not help at all. So one of their own warrantied cartridges has broken one of their printers (unfortunately out of warranty), and they don't care at all. New print head about £170....
Has anyone else had this issue, anyone manged to clean the print head well enough to get it going again, anyone know how to get HP to react and help?