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What you see in the service manuals available online is as good as it gets, I am afraid. The originals are not a whole lot better. This is the case, pretty much across brands, going back pretty much forever. Most techs would be manufacturer-trained and would have their own notes dating to that training to augment the service guides.
I doubt you will find better for the ME than the diagrams in the free manual available at the link below.
Pentax Manuals | Service Manuals
Steve