Have you checked to see if the slide out is still on the rollers? I experienced the same thing with my 35J early on. Check on each end of the slide out from the outside to see if the v shaped rollers are still in position on the tracks that are fastened to the side of the slide out.
Also when I set the level on the motorhome with the slide retracted I used a 4 ft. level and put the slide out side high. I set the level bubble on the mark and not in the middle. That way the camper is level with all the weight of the slide out extended.