Here I go again. We had another similar problem on our NEW trailer on the bedroom slide which has a chain/cable/electric motor driven system. The problem turned out to be a loose connection at a crimp connector right at the drive motor on the slide. In our case the motor is above the bed on the bedroom wall. The intermittent & time delay nature of your problem led me to believe it was temperature related and still may be even with the connector or solenoid elements of the failure.