I get a feeling you are using a recycled cartridge.
Clean and then shake the cartridge downward as if you are trying to get the ink out of it. See if all the colour bleeds consitently out of all the designated holes. If it does then theres no block.
Now try and clean all the contact behind the cartridge and on the printer, that might be dirty contimated with inks.
Try a test print using the printer control panel, normally you hold one of the button while turning the printer on, check the manual for this. If you can see all the colour then your printer is ok, you have problem with your driver in that case
Not sure if your head and ink catridge are separate, if its seperate then I guess your head is gone. The tube or the ink pump might be faulty, the one that leads from the ink supply into the head. But I doubt that since you have many colour thats not working.
Yup for some reason yellow seems to dries up more often.
Hope that helps...let me know how it goes