Umarex UMAREX Air Javelin Leaking

[mojamz]

My Umarex Air Javelin arrow rifle has seen very little use but has been sitting in my safe for over a year. I put a new Co2 canister in and gas immediately began leaking through “barrel”. If I cocked it the leak would stop until fired at which point gas would continue to leak after being fired.

Any ideas how to fix this?

 

[dghal]

I have a single 12 gram cartridge converter on mine since Im back yard shooting after a few shots when the pressure drops it wheezs out the last bit,

Are you starting out full C02
Wonder if it has a dry seal somewhere