Could someone tell me how to remove/reinstall the gas plug and cyl for cleaning? I do not have the DSA manual. The lever will rotate leaving the lever unit loose and the letter "A" to the side, but can't figure out how to remove it. Also, should I be able to turn the gas regulator by hand? Unless I am doing something wrong it won't turn. Thanks for the help...the gun is on the vise as we type!