When you hit the switch for the slide that ins't going out, is there any noise created like a motor is running? As the previous poster mentioned, something like that could be a shear pin. You obviously have battery otherwise the kitchen slide wouldn't work.
The slide in my trailer had a fouled ground. I traced the ground wire back from the motor and found where it attached to the frame. The ground wire to frame connection was very loose with some rust where the connection should be touching metal. I sanded the frame down in that small area, added a new lock washer and really tightened the bolt down to the frame. Hasn't been an issue since.
I love me some land yachting