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I would advise you to try doing two or three Head Cleaning cycles, using the Maintenance functions in your printer's software.
Allow at least 5 minutes between Head Cleanings. This allows waste ink to soak into the printhead, thoroughly.
The purpose is to rinse the printhead with a bit of wasted ink. And that will wash away, probably, the ink that has turned greenish with time and aging.
I have often heard of 'printout greenish' problems that were solved this way, so I think it will work. Let me know, please. Thanks.