Digital BW, The Print

Hi All:

Has anyone else noticed an unacceptable degree of variability from 
one Piezotone Selenium cartridge to the next?  I just put a 
new "color" cart in my 1280, printed a file I had just printed with 
the previous cart, and got an unusably dark print.  (And continue to 
get them.)  Anybody know what's going on here?

Thanks.

Chuck