How do i fix an odomiter and tripomiter after the went out.

This is for the mercury cougar, If the trip and speedo is not working when driving I would bet that the tiny gear conected to the speedo motors is broken, It happened to mine. It's easy to fix if you are mechanically able to under stand. The part is available on ebay for a steel gear or go to your local junk yard the thunderbird and cougar or the same. Take out the instrument cluster and remove the speedo assembly, there is a cluster of gears together, remove the gear cluster carefully and you'll see the tiny gear missing teeth. Remove that gear and do the same at the junk yard but beware others my have to same problem, I search two cougar and three thunderbird before finding one that was not broken, I hope this helps. P.S. the main cause of this gear breaking is pushing the trip button while driving. Or age of the car.plastic gears don't last forever.