I have the same problem with mine, spoke to a family friend who's a mechanic. The volkswagen speedo is controled by a series of plastic spokes. Over time they get worn down and the teeth may not be touching anymore. I've noticed with mine it works more in the winter (when the pieces of plastic are very cold, and not as soft as a hot summer day) however if they work when I start the car, the will not work if I turn it off then back on. The only thing you can really do is get a used gauge cluster, bad part is the mileage is electronically controled, and only vw dealers have the ability to change it to match your vehicles.