Digital BW, The Print

I've decided to try BO printing with Eboni ink in an old 825 before committing my workhorse 
1280 to the cause.  My understanding was that the print heads in the 825 and 1280 are the 
same (they use the same black dye ink cart).   

In all fairness, the 825 has had a tough life and even with OEM dye inks is a little prone to 
clogging.  The printer is totally unreliable with the eboni ink, though.  I can run four 
consecutive nozzle checks and get four different results; rarely is one of them perfect.  
Running a cleaning cycle usually gets a good nozzle check immediately afterward, but the 
second nozzle check is flawed (missing at least one line segment).  All the prints I've made so 
far show banding.

Does anyone have any suggestions?

thanks!
-brad