Digital BW, The Print

I have an intermittent problem. I can get a perfect print and then the 
next one will have solid dark (maybe black) streak of wet ink down the 
left side of the picture about 1.5" wide. Ink is just gushing out for 
about 1.5" of each 13" pass. It sounds like an unsealed cartridge but 
I've tried both factory loaded UT2 and spongless cartridges I loaded 
myself with UT2 inks. Any Ideas?

Robert