Have not looked at my Seneca yet, but on my Previous National Seaview, the slide had a Power Gear electronic motor, and on that motor, there was a small lever on on far side of the motor housing (away from the gears). Basically it acted as a lock. If pulled toward me (on my coach), it locked the slide where ever the motor stopped, when pushed away from me it basically disengaged the motor. When I would load lawn chairs in the basement pass through, I would often accidentally move that lever from the locked to unlocked position. While the slide never actually came out, the bottom would move out 1-2 inches when I would start driving. I always knew as I would get unusual air noise if I had hit it, and the slide would not be flush on the bottom. Simply moving that lever in and re closing the slide would then fix the issue.
If you look at the pic on KWIKEE 520317S Slide Out Motor, 12 Volt Dc from UnbeatableSale at SHOP.COM
the switch I am talking about is the brass loop you see on the end. Basically it slides back & forth. If you have that on your slide motor (look in the top of the compartments under the slide), try moving the lever and re-closign the slide out.
Hope this helps!