I just found out my grandson has a canon printer that uses the same head so Im considering giving it to him to try in his printer. Although now Im wondering if its possible that if the printhead is electrically bad that it might screw up his logic board in his printer and then I would owe him a new printer.
Don't do this!
A defective print head can damage the logic board, and a logic board that has been damaged this way can damage another print head. Even if I think Ink starvation is the cause of the problem, I cannot rule out that an electronic failure is present. You risk ruining your grandson's printer by asking him to test the suspect print head. Swapping print heads between printers for troubleshooting is generally a bad idea.
As all nozzles work when starting a print job, but the magenta fades away after some printing, I think the problems are not with the ceramic nozzle plate which should be left alone. I would do no cleaning attempts to the ceramic nozzle plate.
Instead I think the cause of the problems is ink starvation. This could be caused by a clogged cartridge or a clog somewhere in the upper part of the print head, either in the ink inlets or in the fine ink passages. As a new OEM cartridge made no difference the problem is most likely in the upper part of the print head.
So I would disassemble the print head and force Windex, pharmacist's cleaning solution, or even plain tap water through the ink channels from the ink inlets using a syringe and a suitable adapter.
Here is an adapter I made from a Luer-lock needle and a needle scabbard:
Cleaning a print head outside the printer is always risky and even more so when taking the print head apart, You risk ruining not only the print head but the logic board as well. But as I think the printer is already considered a write-off, I think you have nothing to lose by trying this cleaning. You might get a working printer.