I have a Roland vg2 640 using tr2 inks. I'm trying to print a black background on a canvas/polyester material however i keep getting lines. Nozzle check is fine, I have done a detailed calibration test, gap adjustment test both of which are fine. Slowed the head down, added 0.5 second (scan interval I think it was) and nothing is working, I've been speaking with Roland for over a week who don't seem to have a clue what it is and I'm getting sooo frustrated! Wasting so much media and ink its making me mad. I have attached photos. Id also like to add that when I do a smaller test print around 30cm it's ok?