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

 

[DHV68]

I have an original Umarex javelin love the damn thing ran out of CO2 so it's set empty for about 2-3 weeks put in a new 88 G and it just started leaking right off the bat tried caulking it tried shooting it again and again just nothing stopped it it drained the whole 88 grams does anybody work on these does anybody have a clue on where to get a manual or Umarex is useless Boomer X is definitely useless anybody has any ideas please