Digital BW, The Print

I have been getting two or three dark bands at the trailing edge of my 
prints about 1/4 of an inch into the print at the end. There is no 
banding any place else. Sometimes a nozzle cleaning will cure the 
problem. Other times not. I am using the MIS Eboni ink, printing BO. 
This also occasinally happens on my C84. Does anyone have a cure? 
Thanks for any help to this aggravating problem.