I know a lot of guys say not to tap on the dist vacuum advance pot, the info about soaking the bottom of the dist with penetrating oil is sound advice, but if your going to have to destroy the dist to get it out why not use a rubber hammer to help get it out, what do you have to loose? I don't mean beat on the dist, just tap it one way and then the other while keeping the bottom of the dist sprayed with a lot of the oil, penetrating oil does no good unless it can get to where its needed, just moving the dist just a small amount allows the oil to flow in the gap created by moving the dist and loosing it, it takes patience and time, go slow and don't get real rough with the hammer