Replacement Valve for UK Webley Raider?

Hey Y'all Last August, while I was practicing for the Pyramyd Air Cup, the valve stem of my Webley Raider broke :(. I understand that this is the Achiles Heel of these guns. Needless to say I've been bumming out because my go-to FT rifle is out of commission. I am trying to find a replacement valve assembly. I haven't had the gun apart so I don't know if any other part of the valve is damaged, so I want to play it safe and just find a complete replacement valve. I have had some trouble locating this part and was wondering if anyone knew where I could locate one. I searched on TW Chambers and most of the other gun spares sites but can't seem to find one. Secondly, since the valve stem is broken I cannot discharge the gun to remove the air that is still inside the air tube. I'm not sure how to de-gas the gun so I am looking for the names of some good airgunsmiths who I could send the action to to install the valve once I procure one? The rifle is the single shot variant of the Webley Raider. Possibly made by FX? I am pretty sure it was manufactured around 2001. Any feedback is greatly appreciated because I am anxious to get my Webley back up and running. Thanks,Nico