Wiring trouble shooting question

Almost certainly under the corroplast and then an extendable loop under the slide. Extend the slide and get underneath and look at the bottom. Usually there will be a loop of wire suspended by springs, so that it can extend/retract while keeping the wires tucked up. Good chance you will find your fault there too, since that is the least protected area. Maybe where the wires pass through the frame. That's a likely pinch or scrape area.