A friend with a FWB 65 pistol is a bit miffed that it has jammed with the side lever fully back. It won't release from the ratchet arrangement to close forward; he's capable of carefully stripping it and releasing the piston but is interested to know what possible cause to look for.
Any pointers would be appreciated, yes I've confirmed the lever is pulled right back as far as it goes.

Cheers
torrens