Printer cleaning: How to clean Canon print heads: Cleaning the print head
At first I would try a deep cleaning ("Maintainance", Deep cleaning"). If this method shows no result after three or four tries, stop that: It uses a lot of expensive ink. Try something else.
If deep cleaning shows no results, clean the print head by hand.
CAUTION! Avoid spilling ink on your clothes, carpets, furniture. Ink spots are hard to remove.
For a manual cleaning, first remove the ink tanks, then the print head. Most printers have a grey lever which easily releases the print head.
Now you need a plastic cup and distilled water. Put the print head into the water. It should not touch the metallic contacts. A few millimeters are sufficient. If you moisten the entire print head, it needs a lot (!) of drying time.
Now leave the print head alone for a couple of hours. Before that you can put some droplets of water on the print head´s topside (where ink gets into it).
You can perform the whole procedure with tap water as well. But you risk calcification, and your print head may get clogged by that. Distilled water will not do that.
When the print head is dry, install it in it´s place, and inserts the ink tanks. Complete the procedure with one to three cleaning cycles.