Lately, I have been having a problem with lines (spaced approx. 1/32'' apart) showing up in a certain tonality of my print. I am printing on an Epson 9600 printer using the Inkjet Mall Quad-tone inks (Sepia & Selenium Tones) and Studio Print Version 10 RIP software. To test what I am experiencing I created a print that went from pure black to pure white and found that the problem shows up between 75% black and 86.5% black. The lines travel in the same direction as the print head and attempts to isolate the problem have been inconclusive. I've turned the image 90 degrees (problem still exists); I've cleaned the print head (nozzle check is okay); I've humidified the paper (no change); I've tried different paper (problem still exists on different paper); I've cleaned the pad that the print head rests on when parked (no improvement); The only time I see improvement is when I switch from the Sepia toned ink set to the Selenium toned set (problem goes away). Any suggestions?

Print conditions: Room - 72 degrees; Humidity - 50%; Paper - Hahnemuhle Photo Rag 308/Epson Double Weight Matte; Ink - Inkjet Mall's Piezography Inks; Printer - Epson 9600; RIP - Studio Print Version 10.

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I can't see the lines in the attached file but you've done a lot of troubeshooting and eliminated issues like paper feed and ink absorption. My guess would be either a bad printhead (more likely) or perhaps the Selenium pigments have settled out. If shaking the carts and running fresh ink through the lines doesn't help, then I would think a printhead replacement would be the next step.