Thanks for the welcome and the advice! It is just the odometer. I found the how to on odometergears.com and it looks do-able, so I shall pursue that as a project for the winter!
Welcome! Is the odometer the only thing in the cluster that doesn't work? If so, there are sources for the gears that make it work. They were made from what appears to be very sharp cheddar cheese, and have a habit of loosing teeth.https://www.odometergears.com/products/BMW/R+%26+K+Motorcycles/42https://www.speedometergears.com/bmw-mercedes-odometer-gearsYou can rebuild you cluster in an evening for about a hundred bucks. A used cluster can sometimes be had for that amount, but usually they cost more. If you aren't in a big hurry, you can watch eBay for parts a Cafe builder is getting rid of.