My ejector pump for a basement bathroom & laundry area, surges when it pumps out liquids. It appears to come on and shut off correctly. However, when we bought the house about 7 years ago, it pumped very 'smoothly and steadily". Now it surges quite a bit and a "sucking" sound can be heard through the upstairs bathtub drain line. Also, some of the water in the bowl of the upstairs bathroom is sucked into the main drain line to the septic tank. You can hear the sound of fluids being discharged through the drain line. Any ideas as to what the problem(s) may be. Thanks