Mine has a manual crank shaft that looks like a half moon that is under the frame on the opposoite side from the slide. I'd crawl under and look for a shaft leading to a gearbox that turns the slider shaft that the motor is hooked to. The manual crank should have come with the unit and will fit the end of the shaft...at least mine does. Hope this helps.
Bart and Tina
2001 Chevy 2500HD 6.0 Silverado 4x4-Banks Power
1997 Jayco Eagle 5er 285BHS-flipped axles