My original MX922 print problem was that the PGBK black and white printhead started to print smudged characters with shadows such that printing was illegible on certain lines and QR code spots were smudged/smeared so badly that they were unreadable.
I too just had the identical problem after buying a new "genuine" Canon QY6-0086 and the PGBK printed perfectly but none of the colors printed on the nozzle check pattern. I too tried the internet recommended printer cleaning and deep cleaning cycles to no avail. FRUSTRATING! However what worked was the printhead nozzle cleaning procedures described in many Youtube videos. I previously purchased a printhead cleaning kit with cleaning solution, syringe and various tips for the syringe which I used when ink dried in nozzles and required serious cleaning. Since my bottle of cleaning solution was used up, I made up a solution that I've been successful with for cleaning plugged heads, 4 oz distilled water, ~10% blue windex (contains ammonia), ~20% isopropyl alcohol and warmed ~30 seconds in a microwave. I removed the new print head and placed it in a plastic container on top of a folded paper towel at the bottom. I placed a tubing on the syringe that had approx ID of the color connections that the ink cartridges mate with. With ~4oz of cleaning solution in the syringe, I placed the tubing tip firmly on top of each color connection and squeezed the solution through the printhead. You will see the solution coloring the paper towel under the printhead. After doing this the first time for all the 4 small connections that weren't printing, I gently wiped the printhead and reinstalled the printhead and the cartridges, I printed a nozzle print check and knew I was on the right track because the magenta printed OK but I still had nothing from the cyan, yellow or small black cartridge. I again removed the new printhead and repeated the above same cleaning sequence three times on the three remaining colors that didn't print. I also left the printhead to soak on top of the paper towel for 2 hours. Upon wiping and replacing the printhead back into the printer and performing a printer "maintenance" clean, I again did a nozzle check pattern. SUCCESS!! The nozzle check pattern printed all colors perfectly!
I'm not sure why a new, genuine Canon printhead would require severe cleaning in order to get the small cartridge colors to print while the PGBK big black cartridge printed fine, but it worked for me and I have my MX922 printing like new again instead of having to go out and buy another printer.
