You might want to go to the search bar and type in "slide out manual operation". There are several old forums on this topic. It seams the slides manufacturer has a lot to do with the fix. On some slides the manual crank goes into a hole on the opposite side of the trailer from the slide, some are a small bolt on the back of the motor accessed by a hatch in the underbelly. I saw some needed you to create a hatch in the underbelly.
Phil, Michelle, Logan and Wyatt
2006 Dodge 2500 Heavy Duty 5.7 Hemi
2012 Rockwood 8312ss