My GF needs new ink cartridges for her HP deskjet 3420. She bought some refills from tescos ages ago which unfortunately were rejected by the printer (so she told me, i didnt actually see what the problem was) and so bought some original HP cartridges instead. Anyway, she needs some more now and i was wondering if the re-manufactured print cartridges on sale at various web sites are any better compatibility wise? Should we save some money and get some or are they not worth the risk?