You seen Trev's site? http://cinedux.com/challenger-arms-corp.php
I got a valve unit from Peter.I forgot to tell him I shouldn't be trusted with a screwdriver! Apologies Peter.Anyrate,I'm now after another valve unit(the one you can drop in as simple as an AA battery(!). In order to get my beautiful 8GM CO2 powered rifle going once more!!!!!! Trev