In ground pool about 3 years old, with elevated spa. Jandy system, pool is 7x15 irregular shape 14,500 gallons and spa 750 gallons. A few days ago I noticed after pump turning off, a few a couple of hours the water in the tub started going down I first thought it was a leak but then noticed the water in the pool rising. A friend told me to check the check valve I did and noticed the plastic flap dangling in the window with the spring broken. Is this difficult to fix and if not, what are the steps in fixing it? Any help I will greatly appreciate.