I have a vintage Motobecane Grand Sprint. I am trying to remove the fork and headset to grease the bearings but the cone shaped[?] expansion nut is jammed inside the tube, preventing me from getting the stem off. I tried tapping down on the bolt after loosening it; that didn't work so I hit harder and that didn't work. Finally I hit it hard enough that the bolt blasted through the expansion nut, but the nut didn't move. I can not twist the handlebars or stem. I tried heating it. My next move is to cut the stem so I can get a bigger tool inside to knock out the expansion nut, but that means a new stem of course.