I just had my floor of the fridge slide replaced. 2 yrs old and it was rotted through. The outside corner that was affected was right below the fridge (so I could not replace just a piece like Ray did).
The area was located above the center of the two tires. The shop that did the work believes the water came from below.
The metal strip that covers the interface between the slide wall and the floor HAS to be sealed on both the top and bottom. The caulking on the bottom had failed as well as some portions on the top.
They pulled the slide out and put it on stilts while replacing the floor. I am not sure if they pulled it completely out or did it like the guys in the video below.
The video below (not my rig) shows how the stilt concept works.
$500 parts 16 hrs labor ($2k)