Have a 1979 Koga Miyata I just recently received in great shape. I wanted to raise the stem a little and I cannot get the stem to release. I have loosened the allen screw then used a hammer and a piece of wood but no matter how hard I hit it I cannot get the stem to release. I have used wood, a towel and direct hits (including a gouge on the stem itself which made me sick!) Any hints or tips to get this thing to release? I have hit it as hard as I feel comfortable and the wood has huge dents in it where I used it as a cushion.