Have you tried multiple cleaning as it may take a few cleans to clear. I know it uses ink but usually works eventually. I do not think you should try and remove the heads, this utility may help as it gives a stronger clean than the native cleaner. You can buy cleaning solution and try and get it down the spigots with a syringe, others on the forum use diluted Vodka I believe. When you remove the cartridge you can see the hollow spigots at the bottom of the carrier.