Hi, not too mechanical, got a good deal on a 357xp that has the auto decompression valve. I have heard this can be a problematic set up. I want to put a manual valve on it and seal the other end correct? Can I do this and also what do you think it would cost to have it done at a shop? I am nervous about attempting this but might tackle it if you guys say it isn't too tough. Thanks, Russ