Printer cleaning: How to clean Canon print heads: ...no success yet...
If all that fails to work you have a bad hand.
You may repeat the procedure with a nozzle cleaner (print head cleaner) or isopropyl alcohol (IPA) from your local drugstore.
You also can buy cleaning ink tanks. I personally don´t think much of them: They are expensive, and the results don´t convince me. It´s more effective to "bathe" them as shown before to eliminate persistent clogging.
Ultrasonic cleaning systems, as used for glasses or adornment jewellery, can perform miracles.
If nothing helps...
...you need a new print head. That´s no affair with semipermanent print heads. One will cost you only a trifle more than an ink cartridge. That´s different with a permanent head: This will cost you real money.
If your warranty is still valid, you may send a printer with a permanent print head to Canon. Do this only if you always used inks made by Canon.
If your printer frequently needs manual cleaning...
..could this be due to the use of cheap ink or a soiled or broken cleaning unit.
The cleaning unit may break down owing to numerous changes of the type of inks and/or low-grade ink.