You can try reblocking it with a sequence of fill level percentages:
hammer reblock <fs> 10
hammer reblock <fs> 20
hammer reblock <fs> 30
hammer reblock <fs> 40
hammer reblock <fs> 50
hammer reblock <fs> 60
hammer reblock <fs> 70
hammer reblock <fs> 80
hammer reblock <fs> 90
Each PFS needs to be independently reblocked.
-Matt