I believe you'll find that the nut with the safety clip going thru and holding it on is the nut you turn to manually bring the slide in'out.. If you look, in your photo, it's attached to the gear box part of the motor/gear box assembly. Have the same set up on my bedroom slide on our Lexi. Front two slides have the manual nut accessable from the storage compartments just under the slides. Bedroom slide only accessable from under the bed.
Takes a 5/8 inch wrench or socket.
Steve & Cheryl + Zoey, and Ziggy, our furry kids.
2012 Forrest River Lexington 283ts
Toad, 2013 Subaru XV Crosstrek