Tuning 1987 Benjamin 342 pump cup stuck in chamber.

The pump rod seal (cup) is stuck in pieces to the top of the air chamber and side of tube. (This rifle was working a year ago, never re-sealed.)


Any ideas on how to remove the little pieces without removing the air chamber? 


Ive considered putting on a new seal cup and just pump it trying to blow pieces through ,but that would probably stick in the check valve.