While you are on the site, in your browser find and click "Add to Home Screen" A CGN beaver app icon will then be created to your phone that is directly link to the site.
Note: This feature may not be available in some browsers.
You're better off ordering the parts and fixing it yourself, it would save you money and time. The 357 is a fairly simple build that can be dismantled very easily. What part is broken on your pistol?
Does it leak from inside the gun where the valve is located or from the piece that pierces that co2 bulb? I can send you a replacement seal if you figure out what is at fault because I don't plan on fixing my 357 any time soon.
Crosman US has pdf files with the part numbers. First link is list of guns. Second link may be yours. Cartridge seals are available and cross compatible with most Crosman CO2 revolvers.