I have a 12,000 gallon pool and raised spa. The Spa level drops about a foot when the pump is off. In my research online it sounds to be a check valve that is failing. When I look at the videos, I can't seem to locate where this valve may be on my system. I took a few photos, one of which is where I think it is, but I'm not sure. Do I just remove this cap while the pump is off, find the valve, and replace with the same part?