Just this week we noticed that there must be an air leak somewhere in our pump system - when the pump shuts down, there's a whoosh of water leaving the pump strainer basket area. I cleaned the sealing surfaces of the lid and o-ring with the silicone o ring stuff and that seems to be sealed (you can tell the seal breaks when you take the lid off). So where are other logical places to check for air leaks? I assume that if the air is leaking in from somewhere else in the pump that we would see some water leaking out?