Need a lesson in livewell opeartion. Have a new to me 2007 Z20. Boat has the manual livewell switch with RECIRC on the left, EMPTY on top, and AUTO on the right. Even though I found the manual online and think I understand how to use it, it always fills with water no matter what I want it to do. My guess is there is a flapper that is stuck or not working. Does that sound right? Is this a common problem and easy to fix? Thanks.