It's probably a rack & pinion gear slide mechanism, maybe Power Gear brand (what Fleetwood mostly uses). If so, it sounds as though the slide isn't going out quite far enough. The top is supposed to touch first and the bottom moves a bit further before stopping. That brings the slide up level and seals all the way around. There is usually a limit switch that stops the travel, plus the motor control probably has a current (amp) limit that shuts it down rather than overload (in case something jams). You might even have something stuck between the bottom of the slide and the wall, so that it doesn't go quite all the way.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC