Digital BW, The Print

I have an Epson 1280.  I recently switched from the MIS VM inks to 
the Ultratone inks.  Since then, I've had terrible clogging 
problems.  The yellow position (lightest gray) is the worst--it clogs 
so that on the nozzle check, the last 1/3 of the bottom line 
of "yellow" does not show.   This has been a periodic issue with this 
printer since I went B&W.

The last couple of weeks, ALL the color nozzles have been erratic.  
Last week all but the yellow cleared with a couple of cleaning 
cycles, and I could print with almost invisible banding.

This week the color nozzles wouldn't clear until I put the Epson 
color inks back in the printer.  At which point all but the yellow 
cleared immediately.  I'm going to just print color for a while and 
see what happens.

I print mostly on weekends, but I try to turn the printer on and off 
midweek.  Any thoughts?  I've already tried the Windex/Fantasik 
tricks.

Thanks,
--Peter