There was an article in the Star magazine several years ago that detailed very well the repair of the VDO odometer. It involves filing the flats off the shafts, sliding them out, cleaning lubricating and then sliding the shafts back in and crimping the ends.

The alternative if you don't need the trip odometer, is to remove the plastic spur gear that connects the two. This removes half of the friction load and allows the main odometer to work again.

Good luck,