Digital BW, The Print

Looking at the printer from the front top, the print head is making very fine, 
parallel, coloured  lines on the left-hand side of the print.   There are four sets 
of two, each set spaced about 5/16" apart, one set for each colour.  Starting 
from the left they are: black-light black, cyan-light cyan, magenta-light 
magenta, yellow-light yellow.   Just one set of each; none on the right side.

I did a search under pizza wheel marks, but these don't seem to be the same.  
I can see no marks before the paper goes under the print head, and then the 
lines appear before the paper gets to the rollers.  

They first showed up yesterday, but they went away andI managed to get one 
or two good prints, but now I'm just trying to get the last one done, and I'm way 
past my deadline on these prints.  Can anyone help with this, please?

Thanks,

peter