I have tried ordinary nozzle clean (twice), and deep clean about four times. The check pattern is 100% for all the other colours, but for cyan, the first block is a bit stripy, and the second block is completely blank. I very seldom use colour, so I have no idea how long the problem has been there. Could the nozzle have become blocked, and the blockage become "cooked" in with use? Any ideas what I can do to clear it?