If there is excessive gas in the cylinder and you don't want to turn it over to blowout the gas you can always suck it out. small shopvac, fish tank airpump supply hose, and duct tape, stick the smaller hose in the shovac line and duct tape it to seal of the diff. in size. sounds ghetto I know but you would get all the gas out before moving the piston in the cylinder, then like HipSi said spray WD 40 in the plug hole but you'll need a longer stem to make sure that you get it on the walls instead of puddling it on top of the piston.

Best of Luck bro.