Have you siliconed the wiper seals on the sides and top of the slide out? I sometimes would push or shake the slide as its going out. By looking underneath when open a little you will see the slide mechanism. Some are rack and pinion with electric motor, some hydraulic powered, and some have side or end mechanisms. Call the parts dept at Gulf Stream and they can tell you the supplier and part number
You most likely have an in the floor mechanism. Meaning two arms underneath that extend and retract your slide. Some are electric motor driven, some have hydraulic actuator and pump. If they are not sync'd (move together) it may be a mechanical failure of the gearhead at one side (front?). There is a torque tube running from one arm to the other that is suppose to keep the front and rear together . . . You will want to find a competent Tech to look at this for you. If you are in Chicago area, I'd be happy to do it.