Even if you didn't find the tech manual, you still won't have the test bench and other diagnostic equipment the factory techs use to recalibrate things and diagnose problems, so it wouldn't do you much good.
You make it sound as if the Canon test bench is composed of equipment which has be developed for some high tech endeavour.
In reality the most apropriate tools are:
2...Toothbrush (one hard, one soft bristle).
4...Set of screwdrivers (small)
6...Anti-static mat, etc..
I spent much of my time repairing telephone exchanges (both electro mechanical and digital) and the tools required to do most electrical and/or mechanical repairs in a service lab are not exotic.
Jonathan - whilst it may be beyond your capabilities to undertake such a repair, there are plenty of other people for whom this would be more easily done at home than shipped to Canon.