Digital BW, The Print

Can anyone tell me if "banding" - this may not be the correct term is 
either normal or fixable on an 1160? Specifically when printing black 
ink only, there are faint lines visible thoughout the print.

My print is a landscape orientation rotated 90 degrees, the striping 
follows the direction of the print head, and is only visible on close 
(no loup) inspection. On a 5X7 print the lines are invisible when 
held at arms length, very visible when held closer.

I am using Epson Photo Paper, Epson cartridge (new) have done 2 sets 
of 3 cleanings separated by an MIS purge print (which showed visible 
lines in black, magenta,and cyan, but yellow was fine.

I have tried printing in "automatic" mode and all variatios 
of "enhanced". The file goes to a print spooler file, which makes no 
difference. My computer is a 1.25GHz e-mac, i have been printing 
under OS 9 due to limitations of the printer software in OS X. My 
file sizes are 15MB jpegs from a Pentax DS, they print flawlessly on 
the 825. (I want bigger prints!)

If I print the same photo in color at the same resolution the print 
looks fine.

Have I got a problem or am I running into the limitations of black 
only on the 1160? I have also printed black only on an Epson 825 at 
5760 dpi, the banding was there but only visible with an 8x loup.

Any sugestions?

Your input will be highly valued.