Our Bedroom slide did the same thing. After removing the bed, and covering material to get to the slide mechanism, I found a wire had come loose in the plug for the motor. After re-seating the wire, and plugging in back in, I used a wire Tye-wrap to keep if from working loose again, actually 2 wraps, one on the wire pair, and another on the 2 connector half's. This has fixed the problem for 4 years, we hope it is permanent.
Wildmanbaker