Agreed, reproductions of the photos in the manuals is not good and they get pretty dark. I have seen varying degrees of success with photocopying, but I think the photography was not the best even in the original manuals.
It would be an interesting project to possibly recreate the action shots and develop a new digital version of those manuals with better photography and additional detailed examples and descriptions of the service being performed. I think the tribal knowledge is out there, just a matter of bringing all of those services together in one place. Sounds easy enough!