Reseal a 2240 (ish) ?
It's a custom build super stubby but the CO2 'system' is kinda stock, just needs the small carts (which I'd provide). Just cant get the carts to seal and have never done it myself.
Every time I search I get too many references to old posts.... starting fresh...
I had a 2240 that started leaking.
It was the seal that goes where the nose of the cart fits against the valve.
I was going to try an oring, while I ordered the correct part & waited for it to arrive, but I found a complete spare valve assembly in my parts box, so I swapped out the seal and its been working fine ever since.
Try warming up your rig with a hairdryer. Focus the warm air on the area where the valve sits, outside the frame & tube, thru the loading port, and down the CO2 tube, then while it's good and warm try piercing a cart.
Sent you a pm.....
Truth is Stranger than Fiction...