Thanks for the speedy reply!
This slideout does not go all the way to the floor - the bottom is about knee-high inside the trailer. It also slides fine now that I've lubed it. Next thing is to replace the handles for pulling it out that the FO popped off because of how stiff it was. At least the trailer was clean & cheap - though it'll be getting all new wheel bearings & tires.
There are no plugs around the inside of the slideout & the bottom of the slider itself is smooth plastic - no wires showing there.
I'm guessing the wires must be run through the back wall into the ceiling or maybe in the bottom. They are not on top of the slider. My hope is to find out where they are run so I don't have to tear everything apart.
Yes - a battery "closet" light might be in my future...