There are 2 limiting factors to the jack. The mechanical limit is fixed by the machining within the jack shaft. The electrical limit is set by 2 limit switches in the motor.
Run the jack to the retracted limit using the motor. Remove the motor head and using the hand crank retract the jack to it's mechanical limit. Now extend the jack using the crank handle1 1/2 turns. Replace the motor head. This offset is a safety factor.
You motor head should now move the jack through it's full range.
Sounds like someone may have removed the motor head at some point while the shaft was not at either extension and got things out of sync.
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