1) take your cluster out just as you would to install guages, but take one extra screw out from the top AFTER you get the plastic cover off.
http://www.mustangworld.com/ourpics/fcar/whtf1.htm
2) the cluster is in 3 different pieces, pull up on the temperature and oil part and set it aside.
3) next pull out the middle part with the speedo.
4) flip it over and note the clear blue plastic housing which holds the motor, worm drive gear, main drive gear and all other pieces of hardware.
5) remove this housing and remove worm drive gear by prying up on plastic tabs on both sides (i used flat head jewlers screw drivers) and rotate clock wise.
6) flip the odometer over so your acutual mileage is facing you and push the main drive gear out towards the bottom.
my problem was that my main drive gear shredded itself against the worm drive gear, leaving a tooth stuck in it. i removed all the teeth stuck in the worm gear and laying around in the housing and will be replacing my main drive gear. the worm drive gear seems to be in decent condition.
Replacement gears can be purchased from:
http://www.odometergears.com/subpages/ford.html
