Place the deck on something that is elevated such as stairs so that just the fork and headtube is hanging off the edge of whatever it is. At this point the deck should be touching the ground and the fork should not be. Have someone stand on the deck and take a piece of wood or rubber mallet and smack the shit out of the top of the fork tube. If it's not coming out, your not hitting hard enough. This method has always worked for me with no problems. If this doesn't make sense then sorry. Explained it the best I could.