Then Helk Yeah it's worth it to fix the seal.
I have one of those and it does the same thing. I just keep a cart loose in the chamber, and tighten the piercing knob on the bottom
only when I want to scare some pests off the property. It goes through a cart very quick due to the leak, but it works in a pinch until I figure out how to fix the leak. I've got a red laser on the bottom rail and it's fun to shoot BB's as fast as I can pull the trigger.
Scares the Helk outta what ever I'm trying to get rid of.
FWIW; I also have the Daisy Powerline model 617x semi auto CO2 pistol in 177 pellet/BB combo. It also had a seal leak at the cart piercing interface. Looks like they both have the same rubber o-ring gasket/seal at the cart neck.
Here is how I fixed the same problem on my old Crosman 454 BB semi auto CO2 after 20 yrs of service.
I simply picked out of my Harbor Freight O-Ring Collection container ($10.00) a suitable size o-ring and fitted it to the cleaned out area of the old removed seal (O ring) and pressed it into place, lubed with Pel Oil and screwed home the new cart and it's been holding gas for months now.
I know ------- Not Olympic Quality shooting-------But they sure are Fun as Helk to Play with. And really that's all I expect of them------- and they DO NOT Disappoint !!!!