Digital BW, The Print

I've been black only printing with an Epson 1280 and a MIS continuous
feed system for the black cartridge. A few days ago I encountered
banding problems that cleaning cycles and purge prints would not cure.
Eventually I lost all my black nozzles. I followed the troubleshooting
guide on the MIS site at
http://www.inksupply.com/index.cfm?source=html/cobratrouble.html after
suspecting it was a foaming problem. After three days of frustration
I'm giving up and just buying a new cartridge. 

For those running a continuous feed systesm how often do you have to
deal with foam buildup that requires bleeding your cart(s) or siphon
breaks?

-Jim