First, double-check to be sure something is not on the floor under the slide room that won't allow the bottom of the room to close completely. Most common cause is a piece of carpet is torn off the floor and gets stuck under the slide room. Or a kid's or dog's toy sneaks in behind the slide room when it's closed, then when you open the slide the toy falls down to block the slide from closing completely.
Grumpy ole man with over 50 years towing experience. Now my heaviest trailer is a 7,000-pound enclosed cargo trailer, RV is a 5,600 pound Skyline Nomad Joey 196S, and my tow vehicle is a 2012 F-150 EcoBoost SuperCrew.