To remove the lever, unscrew the black ring around the shutter button. That ring is metal (brass I think) so dont put the vise grips to it. I had wrapped it with friction tape and it unscrewed out (counter clockwise). the shutter release button stays in place. The main (plastic) advance lever is probably free floating with a slot underneath it for that metal tab to fit into. Its the metal tab that actually advances the film spool. That metal tab is also free floating with a notch that fits into a keyway for the spool axle(?) so the advance lever is just to provide extra leverage. That's as far as I took it to replace my lever.
Let me know if that helps.