I backwashed our filter today, and after returning the haward vari-flo valve to the filter position, it seemed to be working fine. Later, I happened to be in front of the house where our backwash piping dumps into a storm sewer, and there was still water coming out. I went back to the pump, it was running empty, and the pool had drained down below the skimmer. What in the world?? Is it possible for those valves to fail such that the lever can be rotated, but the mechanism inside doesn't turn? Also, is that valve rebuildable, or is it easier to just replace it? The rotating lever has been VERY difficult to turn since we've been in the house (1 yr), and has gotten worse lately.