TurboPrint & PrintFab

I have a Canon s750 that used to print fine until I upgraded to Ubuntu Dapper. I stopped using the printer but decided to try it again. I installed the latest TurboPrint and installed my key. the license shows up as private so the key is still good!
I cannot print anything with anything but color-no black. The printer sounds like it's printing and the paper feeds but no black copy at all. A test page does show black ink though either run from xtpsetup or from the Ubuntu printer dialog.
Help?
thanks

an update- now a test page will not print black either. Changing to B&W or Grayscale produces no printing. Again, the printer runs, paper feeds but no copy. There is ink in the black cartridge, I have cleaned the heads.

Much to my chagrin, it appears that the black ink printhead was dirty. I have cleaned it 10 times and there is finally some black printing happening. sorry about the red herring!