I have an SX600FW. Mine won't print blue. I've spent nearly 2 weeks trying to fix it, clean it, run diagnostics. I've wasted a fortune in ink cartridges which seem to go through about 4 or 5 head-cleaning cycles before showing up as empty. Even then, they are still about half full as you can hear the ink inside when you shake them.
I've gone through a complete set of cartridges, AND tried 2 brand new blues. So far I have made no difference whatsoever in the print quality.
All I can suggest is if you're willing, try taking it apart and getting the print head out. Clean it with alcohol and see if that works (it might, it might not - who can say). Other than that, toss it and buy a decent make. It'll cost you less in the long run without so many wasted cartridges and unusable printed pages.
Pete, July 2010
