Digital BW, The Print

I am in the process of switching from MIS Ultratone inks to Piezotone 
inks in my 7600.

I used a set of MIS cleaning carts to run several cleaning cycles and 
all was well.

Today I took the cleaning carts out and installed the Piezotone carts. 
However, the Magenta cart refuses to be recognized. The light goes off 
when I inser the cart, but when I set the ink lever the Magenta ink 
light comes back on.

At this point, no Magenta carts in my possession will work. I tried 
reinserting the cleaning cart, the new Piezotone cart, the MIS cart 
that was in there, and even a brand new Epson Ultrachrome cart. All of 
them have the same affect.

I tried wiggling the carts, shimming the cart, and cleaning the chips 
and the chip contacts.

Any idea of what else I should try?

I'm teriffied that Epson support will give me grief for using non-epson 
inks.

James