Epson 7900 nozzle "clogs"- ink selector/damper issue?

Hi, my Photo Black channel has been “clogged” for about 3 weeks. I’ve done a series of cleanings even a Service Man CL, but I still get an almost non-existant Pk nozzle test print. All other colors test excellent. I switched over to matte black and “voila!” I got a near perfect nozzle test print. Encouraged I switched back to Photo Black but the same “clogged” condition returned. Instead of a clogged nozzle, could this perhaps be a damper/ ink selector problem? I’ve tried the wiping of the print head with Piezoflush, cleaned the Flushing Box numerous times, cleaned the capping station and replaced the wiper blade. My printer is 3 years old , have not had any error codes displayed,I read somewhere on this site that the ink selectors/dampers should be replaced almost yearly. My humidity level (it’s upstairs) in the room its in runs about 40% RH. I don’t print as often as I’d like, so non-use could be a factor also, however, I did print at least every other week. But if I get it printing again it will see production everyday even if just to keep everything working properly. Any advice on whether it could be an ink selector issue or not, will very much appreciated, Thanks!

This is a damper issue. Generally these printers need to switch regularly between PK and MK in order for the damper switch not to go bad. Even Epson’s own service notes say that the damper assembly needs to be replaced every 2 years (even when regularly switched).

It’s about 280 from CompassMicro. If the printer is out of warrenty and you are handy with tools (or no someone who is) it’s a fairly simple replacement as long as you have the Field Repair Guide ( has this).



I assume this advice would be given to R3000 users also because it also switches between MK and PK. I have to ask, what do you call regular switching between PK and MK?


In a normal working environment when the printer is being used every day, a switch happens nearly every day (or more than once a day). At a minimum it should happen once a week if you want to keep the switching damper from drying out. The other option is to just never switch the damper and use the printer as a single K machine, but you always face the chance that an auto-switch might happen in the future and then mess the damper up in both directions.

Every switching damper that I have come across has had this issue, but the x9s more than any other printer seem to have this issue. (add it to the list)