Benjamin 422 disassembly help.

[Jackrabbit1957]

I have an old Benjamin 422 semi auto C 02 pistol that needs new o rings as it leaks down very quickly. I have got it apart as far as I can go but cannot get the last seal/ o ring out of the pressure chamber. My question is what method is used to get that seal out and does the rear of the pressure chamber come out? I would like to clean up the brass sealing surfaces and replace any rubber parts.
Thanks in advance.

 

[Ascot500]

I rebuilt one many years ago but I don't remember the specifics. You can find a cross section of the 422 at jgairguns.biz
For orings that are hard to reach, I have made a pick from and old bicycle spoke.