Rescusitating epson 7600

In trying to revive an epson 7600 that’s sat for some time. Among other things, we’ve replaced the dampers and most recently the print head. A problem before replacing the print head was that there were horizontal bands of black in the yellow that was suggested was caused by a poorly seated or bad damper. We replaced the dampers and the issue continued so we decided to replace the print head. After replacing it with a refurbished print head, and obviously reseating the dampers again, the problem continues. Does anyone have a suggestion what might be causing this?