No need to use air on that type cylinder since you can just push it on through. Take off the boots, spray it down with penetrant and use a deep well socket putting cylinder in vice long ways (ends of cylinder facing jaws). I have lead covers for jaws to keep from nicking up cylinder. Should break loose with little pressure. If it doesn't , get out the fire wrench or propane torch and warm it up a little. Don't need to get it smoking hot, you do not want rubber cups to melt or spring to lose tension. Once loose, let cool and push it on through. Probably will not even need heat from my experience.
