Digital BW, The Print

I have been printing with a 1200 and the MIS VM inks since early 
October without a problem.  However, after putting in a new black 
cart (I use prefilled carts)I have consistent clogs in the black ink 
when I first turn on the printer.  Up to now, they disappear with a 
one or two cleaning cycles, but I concerned that the problem is going 
to get worse over time.  Furthermore, cleaning uses ink.

I recall some discussion of a new MIS black on the list which I did 
not follow as closely.  Is MIS using the new black in all of its 
inksets?  If so, this is a bummer.  Is anyone else running into this 
problem?  Again, the only change is a new cartridge.  

Would switching to the Gen 4 (?) black slove the problem?  Any advice 
appreciated.  The only clog is in the black position -- the other 
nozzel tests are consistently perfect.

Steve