Hämmerli Prinz CO2 valve service
With thanks to Mark.
He says: "On all of the Prinz models that I have owned, all but one has held gas. When the one that is the subject of this thread came to me it leaked all of it's gas straight out of the barrel. As with all Hammerli gas pistols they are well made and were designed to be stripped with just a few tools.
The valve is a improved Sparkler design and once released from the pistol body you have to hold the end cap in soft jaws of a vice, as Hammerli did not provide any notches in which to undo the end cap. The only 'O' ring in the whole valve is the one that seals the cap. This should be replaced as even if it is not hard it will be deformed. The valve itself uses a ball bearing that is knocked off a polyurethane ring that then lets the gas flow through the stem and straight to the back of the pellet, no 90 degree bends to negotiate. On inspecting the ball bearing with a loop it was perfect, no marks or pits. On doing the same with the poly ring, which has a concave lip on one side that the ball bearing seats in. Best to mark up this side with a permanent marker.
My poly seat the side that seats against the valve stem body was marked up and scratched. Refinishing that side and checking the face of the valve stem to ensure it was flat and straight. You do not need to try and remove the valve stem from the cap as there are no seals in it, just clean it out and blow it through with an air line or use your mouth .Lubed and back together it now holds gas. It does help to have a Hammerli bulk fill cap, so that you don't waste 12grm CO2 bulbs when testing."