Originally Posted by jl2you
We saw a couple valves behind the panel under the sink, but try as we might, we could not turn the darned things! Didn't want to push it in case they broke off.
The valves might be stiff due to water deposits, especially if they've never been used - they typically turn only 90 degrees depending on how they were installed. If they look like this, be tender working them loose. The connection between the valve cock and ball valve is not very robust. Then you get wet...