I have caused my self some headache. I had to dig up my well head to add a pitless adapter that was left out by the installer. In the process some dirt fell into my well. (I found an old license plate cut to block the oversized hole in the side of my well pipe) My pump has sucked some gravel and the system won't hold pressure. I pulled my pump up, it is a 110v sears 40/60, but I can't find the check valve. Is it in the pump, if so is it serviceable?