Crossman American Classic model 1377 parts?

I bought my air pistol a good 10 years ago and its had a hell of a lot of use and is not really cutting the mustard anymore. When pumping the charging handle(front stock) springs back like the chamber is not absorbing all of the compressed air, and then just flops freely when it should snap shut nice and flush. It still shoots ok, dispatched a crook black bird on the lawn this arvo, just aint half what it used to be.

Any ideas on what I can do or where I can source parts? tried emailing crossman but never heard back.

Cheers

Have a look at the Numrich website

go to Nz airgun website -they're in the know -helped me out with asourcing parts.