Digital BW, The Print

Does anyone use MIS-UTFS in an Epson 9000? I'm having a number of issues, not the 
least of which is that my Y chanel will not unclog. I've had a repair guy in, he swaped 
out heads and did the maintnance kit thing but the clog persists even with the new 
heads! It seems fairly unlikely that the knew heads would have an identical defect as the 
old. 
Has anyone had an issue with bad batches of ink from MIS causing this kined of 
problem? I would like to eliminate the ink as a posible culprate.
Any sugestions/advise (aside from getting a 9600)?