Honestly lots of fans have bearings, if there permanently on they very much have a life expectancy of x years, less if hotter or dustier environments, hence replacement every dozen or so years is not exactly a bad call, nearly all semi conductor electronics last significantly longer when ran at a lower temp.
Congrats on the fix, you beat the odds on that one.
Pretty much no one will issue circuit diagrams any more, oftern basic block diagrams, but beyond that your on your own, do to the amount of stuff that gets copied, it is kinda no wonder though. Equally ever more circuits run on std but programmed chips, hence simple replacement is only half the process. Add in surface mount rework tasks and this stuff is getting harder than it ever has been. One of the intresting circuit digrams you can still get is for apple products though, but i don't believe its through official channels. Even then do to the amount of integrated circuits performing some pretty complex stuff its far more akin to a wiring diagram than a circuit diagram of old. Deep multiple layer boards are also the norm and fault finding gets ever harder.
I use to do a lot of board level repairs, these days its kinda only the special cases or obvious that i even contemplate taking on.