I'd start with checking for 12v dc power at the switch, and through the switch.
I chased a slide power problem for 3 weeks (in my driveway, off and on). Finally figured out there was a dead spot at the end of the "stroke" in the full in/out position. I checked the switch with a digital meter first, it showed the switch to be fine. 3 weeks later, I checked it with my analog, that's when I saw the needle go up, but at the end of the stroke, it fell.