Big Countrys do not come standard equipted with the manual shut off valves. What COULD have happened is the interior cabinet door COULD have thrown the slide out of allignment. Most dealers can check this easlily. When you are outside the coach, look under the slide in question. There are several adjustment screws. The extra force MAY have changed the slide allignment.
This is a moderate to difficult adjustment best performed by dealership personel.
They hydraulic system (standard system) is an open loop system so without the valves (and accompanying plumbing), you cannot isolate one individual slide. It really sounds like an adjustment.