Don't know if it's the same on the RLWS, but on the KPTS you can remove the back basement wall and get at the valves. As I recall it's only 8 screws holding the wall panel in place. I've had the underbelly open, but don't remember being able to see much of the valve, especially as the slide moves "up" to open.
Rob & Kelly, Bella & Brady (Miniature Schnauzers)
2018 Pinnacle 36KPTS
2017 RAM 3500 SRW CTD/AISIN CC LB