There is another style that they used with a pressed in bottom.
I don’t know what years used which one. Its the same
principal inside. The ball is steel and it can rust. That
will stop the ball from moving and jam the check valve shut.
Its easier to solve with the first one I posted and why I
have pictures of mine apart. When you find a replacement
shake it. The ball should rattle.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.