Pelican has a great How To on this subject. I did it and it worked great. Took some time but if you're a gadjet freak & want to know how things work this is for you.
The basic problem with the odometers lies in the fact that a pot-metal gear that was originally press-fit onto the odometer drive shaft often comes loose. When it is no longer adhering to the shaft, there is no way for the odometer to turn. The solution, in a nutshell, is to remove and disassemble the mechanism, and to reattach this gear to the shaft.
www.pelicanparts.com/techarticles/Mult_gauge_repair/mult_gauge_repair.htm
Cut & paste the URL above
and you'll learn how to do it complete with pictures. Trust me... it was fun!
...........b