The Livewell Control Valve should prevent water from coming into the wells during the day. If not then either 1>the cable has slipped in the tensioner at the pump valve, 2>or the valve flapper is clogged with something holding it open, 3>or the valve is bad, 4>or the cable is bent. The plugs are an odd size as most dont carry that size plug. They generally do carry the 3/8″ and not the 5/8″ plugs. BCB Parts c an hook you up. We dont suggest using a plug as often ice lasts less time when it is in water from the lack of insulation. Water pulls more cold from the ice as air is a better insulator, sort of the hypothermia thing. You are not as cold in 70 degree air as you are in 70 degree water and hot water works the same way. Just robs life of the ice.