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!