Hi, I'm Nathan.Sorry to hear that you're having trouble with this but I'll do my best to help you.
To clarify, this is a paid support service. There is no free support for your product anywhere, and it is no longer supported by canon.
I you make a copy, from the glass, how does that come out (test both black and color modes)?
I cannot do either of those, I'm an independent tech spending my own personal time to help with your question.
You may cancel from the help page.
If you wish to continue, under the fee you've already paid, just let me know.
Yes, I sent you a reply above, are you wanting to work on the printer still?
Based on your initial question, that would be the likely outcome anyway, everything here points to a bad printhead, which is normal based on the age.
I can recommend some replacement models for you though.