The two orings on the spindle are precisely separated from each other by the distance between the lands in the body. But the spindle slides back and forth to engage the screwdriver, limited only by the screw-on ends.
The problem is that these "all purpose" designs that have both hex and slot screwdriver ends can slide too far in one direction or the other (you'll note that the knurled adjuster has two locations for placement depending upon how far the screwdriver needs to extend.
So when it leaks from being extended slightly too far in one direction, the oring begins to extrude, and you can't slide it back without shearing the oring.
Turn off the gas supply, wiggle it, and the oring will pop back into place. Too many leaks and the oring loses its seal. Just undo the ends, slide out the spindle and replace the orings with new lubed ones. Once you disassemble, you'll see it's a pretty simple device. The slide on/off switches work the same way and also occasionally leak.