I have a 7600 which I left for a year with no cartridges in it. When I got it going again, the dark magenta channel would not produce any ink (well, just the odd trace). Eventually, I slid the head out, disconnected the ink feed from the damper and aspirated a solid plug of dried ink from the line. After priming the damper with ink, the printer worked, but I was plagued by intermittent nozzle blocks occurring in different channels at different times. I did get perfect prints between though. In the end, I bit the bullet and had the printer serviced by Epson and this included the fitment of a maintenance kit (?pump, wiper assembly and some other bits and pieces). It ws expensive, but the printer was much better behaved after that (they also reseated the dark magenta damper which was slightly out after my fiddlings). So, I would look to a full service.