Freeze damage can cause your check valve to leak. Do not cut plumbing!! You can replace several of the parts. The lid assembly for the 2″ valve includes the clear lid, o-ring and spring loaded flap. The part number is 600-7300(lower image). The oring is available by itself (805-0239) The lock ring is #718-7027. The entire TruSeal Swing Check valve is also available
waterwayparts 