I guess with this portion of the cement moving, a weak spot has been exposed, also the metal clip holding the coping is rusted pretty bad, not sure how long this will last. The guy that installed our liner a few years ago said this would be the last time we can change the liner without doing some repair, and replacing the inner walls.
He said it might cost 20k to redo all the concrete, coping and interior walls. It would probably be like buying a new pool, just they don't have to dig the hole or redo the bottom. Sound right?