Digital (pdf, etc) versions were never released to end users by Yamaha. They were a dealer-only thing. Paper manuals are available new from Yamaha Corp and dealerships as well as used and new online. Any digital ones you see will either be scanned pages of a paper manual (hard to search) or be a bootleg from a dealership employee (deal with those options and your own conscience).
But this forum has a long-standing policy of not wanting to get entangled with those legal issues, so links to bootlegs are against the published rules and will be removed.