J-channel holding liner in corner broke off, liner is sagging

[TRHOD12]

The channel that holds the liner in place in the corner of my pool broke off. I can feel chunks of concrete like material between the liner and the steel wall of the pool. The liner is holding in position on the straight J channel pieces, but the liner is sagging in the corner where there is no longer a channel.

Is this something that I can fix, or do I need to call in pool company to fix this??

Thanks for any ideas.

Blessings,