dont know where you are located, but if in a cold climate heat up the plastic on the dash first with a hair dryer or the plastic will crack in cold weather.. then take a butter knife and pull out the whole clock... the small half circle part next to it will probably come out also... then disconnect the electric wires to the clock.. then look in the back for the bulb (its inside a small black plastic holder(looks like you use a very small screw driver to unscrew it... then go to ford dealer and spend $5.00 to get a new bulb.. screw it into the fitting and then plug the wire harness back on and push the clock and the other piece back in...
