For the past couple days when my system shuts off the pump filter basket water level goes down, almost empties. Then, when the system turns on, there is a lot of air sucked through until water finally begins to fill the basket. This results in air bubbles coming from the jets into the pool. I checked the o-ring it is intact, not really any lubricant left on it though. Not sure what the problem could be but I know that air in the system is not good. Also when I clean the basket and try to refill with water it will never fill up. Please help!