Hi there !
I've had the same problem and the good news is that it has a very easy solution. In fact it's just the big o-ring that seals the reservoir tube to the regulator/action. This is an easy to find o-ring but i advice use an NBR90 shore o-ring. It's a long lasting solution and more suitable for high presures.
The best is let Ripley do the job or an experienced gunsmith but if you preffer doing it yourself even though i strongly recomend not, here it goes:
- First empty the air compleatly from the reservoir.
- Unscrew the allen bolt on the top end of the reservoir to allow removing the muzzle piece that joins both barrel and reservoir.
- Using a special leather tool to unscrew without scratching ( don't know the name in english) unscrew the reservoir.
- You will than see the reffered o-ring. Remove it and put a new one.
- By the way, because you have the reservoir exposed, take the time to inspect the inside for aging and corrosion.
You'll be ready for another 4 to 6 years.
Hope that helps.
- A I R M A X -
Team Walther FT Portugal