If you are searching for Service documentation for what would be considered to be a low, medium, high or production volume office/repro-center photocopier; you will have to get that kind of information directly from the manufacturer/distributor or field service firm. If you can.
Be forewarned:
Manuals are not inexpensive, are generally considered to be proprietary (or trade secret) information, and are (in most cases) clearly identified as such. All of the 'big players' in that I'm aware of firms will refuse to sell a manual--even at several tens of times their actual cost--lest they lose their service franchise.
