Proper Hasselblad repairmen have a jig and a fixture of some sort for everything. And they have factory training. It would be like me thinking I could walk in to Eastman Kodak and do PE's job. Nevertheless, good work CAN be done on more rudimentary tools, if those tools are accurate. I've been in touch with a factory-trained independent on another site, and a getting a feel for what I can and cannot do. The number one rule I have for myself is DON'T fool with a particular adjustment if I don't have the right jig, fixture, or tool to undo my "adjustment" and put it back to spec.
Within my limitations, I am getting a lot of things right, though I might have to make a forge to build a hammer, to hammer a nail.