There is only one motor/gear box per slide. The kitchen slide motor is located at the rear of the of that slide, under the TV area. There is a cut out in the bottom paneling that allows easy access to that area. If the gear box has failed, it is made by Barker Mfg. in Michigan. I took mine in and they replaced the gear box at no charge. If the set screw has loosened up and the gear box is not turning the shaft, that is a easy job to resecure in the correct position. If the gear box needs to be removed, you really need to contact Barker and request the special wrench to make the job easy. Without that wrench, it takes a couple of hours, with it 20 minutes. I've had mine out twice and Barker will accept gear boxes if sent in, so they told me.
http://www.barkermfg.com/our_service.html If you need more info contact me.