Intake leaks cause air in the cannister....outlet leaks produce drips (water leaks). Because of the bottom pump design your in no danger of damaging the filter or reducing efficancy. Another source of air leaks is where the motor housing attaches to the cannister body..although this is very rare. spray all the connections and the valves with a coating of pam cooking spray and see if the problem goes away. If it does then you can use the same methoud to zero in on the actual air leak and fix it.