My Canon IP3000 printer recently started having problems with the black ink. Anything printed in black comes out striped, alternating between dark and light. An example is below.

I've tried the following:

• Running the printer utility's head cleaning and "deep cleaning" a few times
• Running the utility's head alignment
• Replacing the ink cartridge with a new one
• Removing the print head and cleaning the bottom with denatured alcohol

Anything else I can try before throwing this thing away? I'm considering buying a replacement print head, but is this likely to be solved by replacing the head?