If you take out the insturment cluster (volvospeed.com), and take the cluster apart, you can get to the odometer assembly. 99.9% chance you have a broken gear. You need to get a new gear (15-tooth I believe) and replace it. Your cost for the gear should be about $10-$40 depending on who you get it from (they are hard to get and speedo shops know this). Check around with your local speedo shops and hopefully you find someone nice enough to sell you the gear. It shouldn't be more than a 2 hour job if you work carefully. Brains before brawn when working on the instrument cluster!!! Good luck!!!