dang cap...

Howdy,
The fuel cap requires a special tool, but the brute force of the channel lock usually freightens it out. I just grab the tiny thing with a pair of channel lock, and gently turn it. You need to put just right pressure to keep it from slipping and shave a sliver of brass.

Once you are able to execute this move, you will see a brass cup with a button of rubber seal inside. With a pin poke it out and punch out a rubber replacement from a garden hose washer, and you are ready to go.

When the stove does not seem to build up the pressure, it is usually these seals that have hardened up that causes air leak in the fuel tank.