I take it there have been no error messages?
1) The top stripe of Magenta, the one with the segmented or boxcar-like appearance is unusual. I don't recall seeing this particular distinctive pattern before. Are you printing your nozzle check in Landscape mode? Regardless, this looks like a major malfunction at first blush.
2) The subsequent Magenta stripes variable missing ink appears to be due to either a clog or ink starvation.
3) The capitalized letters C,C,C,M,M,M,Y,BK are green but should be black. That the black vertical stripes that flank either side of these capitalized letters appear to be OK points towards an issue with the Magenta but does not rule out major malfunction.
What might be the problem:
A) Magenta cartridge failure. You've tried several other cartridges with no success. Unless all of them are not working properly, and a new OEM Canon Magenta cartridge would definitely rule this issue out, the problem then lies elsewhere. Because we have no idea the condition of your Magenta cartridge, a new OEM Canon Magenta may be a prudent purchase to narrow the list of what might be at issue.
B) A print head clog affecting Magenta. Stop deep cleanings and do soaks and flushes. Only print nozzle checks. This may take days of soaking plus flushes. If you see no improvement at all in the nozzle checks despite patient and proper soaks and flushes, then the problem lies elsewhere.
C) The odd appearance of the top Magenta stripe could in part be due to a dirty timing strip which can cause certain breaks in ink output. This is
one link describing the issue. It may not have anything at all to do with your problems, but a careful and gentle cleaning inside the printer, as well as electrical contacts of the print head, shouldn't cause harm.
D) Check your purge pump function. When the printer is turned off or on standby the print head parks itself over two pads located on the far right of the printer. When you open the lid of the printer, as when changing cartridges, the print head moves to the center and stays there temporarily. You can now see the rectangular foam purge pads which should be blackened from ink. Using a flashlight if necessary, take a syringe or other suitable instrument and flood the top of the purge pads with water. The water should pool on top of the pads. Now close the lid, which should prompt a purge/clean cycle, the result being the pooled water is sucked away to the ink waste pad inside your printer. Open the lid, allow the print head to move to the center and check the purge pads. The pooled water should be gone and the pads may be slightly whiter. If you are unable to pool water initially or the pooled water does not disappear, then you have a purge system issue. Report your observations of the entire process thoroughly here.
E) A print head failure. Only a new print head will fix the issue. I find Canon Sales to be the best prices in the USA but I always search on Google, Amazon, and eBay just in case.
F) A logic board assay failure. Replacing the board is expensive unless you do it your self, something that is not for the faint of heart. It may be time to get a new printer.
