Blue lines showing in Canon ipf5100 prints

[jurtle]

My ipf5100 is showing thin uniform blue lines in color prints. Sometime they are outside the image area, on the border. Sometimes they are very sharp, sometimes faint. Always uniformly spaced, always blue (maybe cyan). Here is a link to an image of the problem. http://bambooturtle.us/ipf5100bluelines.jpg  It is one corner of a print with a ruler included for scale. Any ideas what might be causing this. Canon wants to send $900 tech plus the cost of replacement parts. Please help.

[samueljohnchia]

Looks like a very light head impact on the paper. Try raising the head height and see.

[jurtle]

Thanks for your response. I tried raising the heads and also doing an automatic head adjustment first. The blue lines persist. It is almost as if some of the blue nozzles are getting signals to fire when there is nothing in the image calling for that color. No other colors are showing in this way. So frustrating.