Replacing trailing cable on Canon IPF 8000 - advice appreciated

I have an IPF8000 which is 'nearly working' - print pattern is perfect for all colors with 'return pass' on light grey which prints absolutely nothing. I am assuming (right I hope) that this indicates a communication error since light grey prints perfectly on the other pass. It seems from what I read online that this kind of thing is fixed by either reseating the trailing cable or by replacing it. So it seems logical to try these things.

I have the machine partly in pieces and would appreciate a rough summary of what needs removing in order to get to both sides of the cables. I have the manual which provides disassembly details for various parts - but I don't see any procedure stating 'if you want to replace x you need to remove y' type of thing. Appreciate any guidance - thanks