What i did that works well, is spin the gear a bit by hand to get everything moving again. That Little odometer gear you replaced will start the others moving and in turn the odometer to work, even without electrical power. Make sure every gear tooth is making proper connection when you reinstall that little "gear cover" panel. Also, make sure when replacing that speedo/odo unit, that you get the pins connected from the sp/od unit, onto the female connectors located on the instrument cluster mother board. There are 3 on one side and 1 on the other side. They should all fit snuggly and be free from corrosion. If you don't know what I'm talking about, then you might not have done it properly. Those might also be loose making poor connection. You can press down the middle of the female end connections for a better fit. Then, make sure everything is connected back under the dash and you're set.