Cannon Pro 4000 One color on printhead keeps clogging

[JWatLCSC]

I have a Cannon Pro 4000 that the cyan on the nozzle checks continues to have missing sections, the grey occasionally has spots missing but comes back after a cleaning. The cyan will look good after a cleaning but when I print there is banding and the color is not correct. If I do another nozzle check it shows missing sections in the cyan. I have gone into the service mode and printed nozzle checks also. I have done all three cleaning modes also.

[Michael]

Hello. 

If there is no improvement to the gray after multiple cleanings have been performed, service may be required.  Please contact our phone support group at 1-800-423-2366 for additional assistance with this matter.