What causes this on a test print?

[NitroSigns]

Anyone know what would cause a head to do this?

 

[J Hill Designs]

crap in the nozzles - head soak it

edit: search 'nozzle deflection' for some in-depth reading

 

[artbot]

imagine a row of nozzles jetting ink down at a perfect 90 degrees from the head platen. but a few nozzles jetting at 80 or 60 degrees, the radius of the jet causes the little line that it's been sent to print to be of the right length but not in line with the others, so it's off to the side of its intended target.