IShared inkjet printing 1/2 a page

We have two Compaq Evo SFF running XP sharing a printer over our school network. Worked fine, then one, then the other printing only 1/2 page. HP Injet 960c. Tried all HP tblshtng suggestions like changing cables, turning off/on, deleting drivers and reinstalling, etc. Should we just buy a new injet?