The usual failure mode of motometer odometers is the gear cluster, these parts have been NLA for a very, very long time.
The last time the odometer failed on the wife's R65 I made a new gear by purchasing a bulk pack of plastic gears intended for electric model cars and hand cutting a new gear - not a difficult process, but a very time consuming one.
Purely accidentally I spotto'd a reference to these guys in a K100 conference I participate in.
Fie away folks, even if you are not game to do your own odometer repair you can buy the gears from these guys and give them to your instrument maker.
www.odometergears.com