Sounds to me you have a mechanical problem causing more load on your electrical motor causing it to shut down. As someone suggested if you help the slide by pushing it in or out and it works without stopping it is a mechanical issue. Mine would do the same as you described and I would adjust the potentiometer and all was well for several years. When it started to happen again I noticed that where the slide rolls in and out the rollers dug into the floor somewhat and created some resistance. I removed the groove in the floor by adding some sht metal over the groove and the slide came in again. Try adjusting the pot first then look at where the slides roll on the floor and any other mechanical parts for wear. Hope this helps.