I searched for a parts catalog for the iX7000 but found no free download, so I cannot tell the parts number. I think it might be impossible to get one from an authorized dealer of Canon replacement parts. You might find one on ebay or alibaba but some parts and print heads from the far east are used and maybe defective parts that are cleaned and repackaged in replica foil bags and cardboard boxes to look like new OEM.
I would not change the logic board alone, as the new print head is most likely also defective, either killed by a defective logic board or DOA if it was from a dubious supplier. I think replacing both the logic board and print head would be far too expensive, especially as both parts must be new OEM. If one or both parts is/are defective, the defective part might ruin the good one.
So sadly I think giving up on the printer is the best solution
I couldn’t get my iX7000 to perform the way I wanted it too and now it’s more of an ornament than a working printer, a good replacement was the Canon Maxify...
I had one also, but the PRO9500 is a much better photo printer.
Since it was very bulky and I didn't need a A3 double side office printer I gave it away. The guy still uses it.
But the MX7600 all-in-one with the same technology is my daily workhorse.
Very good office print quality.