Restoring/re-assembling for a friend who has had it for years. I'm impressed by this sr300, never seen one til now. I dont normally repair high end bikes and this one has me baffled. The rear hub on the cassette side has the mounting axle bolt(?) that is too short to put a nut on. How does this work? Plus, it looks like there may be some hardware missing from the inside of the cassette? HELP