If you have a voltmeter stick a straight pin in the side of the wire leading to the jack motor and test for voltage from the pin to tongue ground. If you have voltage there it is either the switch or the motor. If no voltage the inline fuse to the jack is most likely blown.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles