Don't forget leaked schematics and other engineering documents --- which once upon a time were supplied with any moderately complex piece of equipment. It's not surprising then, that the majority of sites where you can find this information are hosted in Asia, former Soviet, or eastern European countries.

I wonder if Google's noticeably worsening search quality in this area has anything to do with where this info can be found, or the legality of it. I remember it used to be far easier to find a PDF someone shared, but now it's very insistent that you're looking for the user manual even if you search for "service manual", and commercial spam has taken over much of the results.

"If you outlaw repairs, only outlaws will have repairs."