First: 1680SS or 1860SS ????
I can't find any information on the 1680SS, but the 1860SS has a cable driven slide box. That means the electric drive motor is mounted inside the trailer, above the slide, and centered on the trailer sidewall (not on any "moving slide surface"....
To access the motor/gearbox, you'll need to do some "snooping"... There is a slide flange along the slide box and you'll need to determine how the flange along the top of the slide is attached. It's probably stapled/nailed to the slide box. Remove that flange and you should have "easy access" to the motor when the slide is extended. On the other hand, when the slide is retracted, you'll need to be a "contortionist" to get your hands near the motor while "crawling or squeezing or twisting" into the small space between the slide and the ceiling to reach the trailer sidewall where the motor is mounted....
Anyway, if it's an 1860SS, it's a cable slide, the motor is on the trailer sidewall, centered above the slide and your "owner's kit" should have included a flexible drive tool to mount on a battery operated drill, insert the tool into the drive adapter on the motor and operate the slide.
There's a very comprehensive "cable operated slide" article located here:
It’s Probably A Bad Day When Your RV Slide-Out Breaks - PopUpBackpacker
Also, here's a photo of the drive adapter tool