This happened to our neighbors in Baja. The motor burnt after the arms bent. The whole mechanism was a toss. So...
We rigged a platform on a forklift to remove the slide-room as a unit.
We inverted the whole darn slide-room for access to the underside.
We glued a section of Corian-type cabinet veneer to the exposed plywood.
We bolted pull-handles to the side of the room.
We un-inverted the room, and slid it back in place.
The slick surface of the synthetic veneer moves easily across the carpet... no motor needed.