"Parts inside your printer are at the end of their service life. See your printer's documentation for details. Contact your dealer."
Following the directions below I was able to get my printer working again. I have a bulk ink system installed and when I first encountered this problem it ended up costing me over $40 to have them do what I presume was the same thing. There is no indication that there is any real threat of ink spilling out of the printer due to overflow from head cleaning, so I have not attempted to further modify the printer.
Found this online:
"Assuming you have completed your modification... [i.e. fixed the problem]
1. first turn off your printer
2. push the b/w + color + stop buttons together and hold
3. push the power on button and hold (so you'll now be holding down 4 buttons together)
4. Don't release all the buttons until you see the light indicator is blinking and then a message display on the lcd
5. release all the buttons
6. push the color button (once)
7. turn off the printer
8. turn it on again."
Another helpful link:
My Bulk Ink System is the IJC C86 Bulk Feed System from inkjetsusa modified for the CX6600. (If you want to do the same make sure to let them know you are going to use it for a CX6600 so they will adjust acordingly.) I have been very satisfied with the system, although I did have to use my Dremel to alter a part of my printer to make it work. Here's photos to show what I did to the printer:
The photo above shows the printer cartridges in place and my finger pointing to the modified bit.
The next two photos show the bit before and after it was modified and shows how I put paper in the printer to contain the shavings from the dremel cutter.
Finally, here is a photo of the bulk system in place. I added some extra support to the plastic piece that was provided to attach the tubing. I had to increase to thickness of the piece that was meant to stick it to the underside of the case and then added paper clips to ensure that it did not come off easily. The scotch tape helps keep the tubing from catching on the ink cartridge carrriage.