I knew exactly what he was talking about. Tape is not necessary, but a slick/easy trick to avoid possible damage. I have loosened quite a few stems, with stuck wedges, with the simple method suggested by the posters above (light whack, support stem) with no issues. On one stubborn one, I got a little impatient and on the 3rd wack I used a bit more force, in the process I apparently loosened my grip on the stem, the result was the stem "slamming down" into the frame. To be fair this was user error, but not an unforeseeable error and if the parts are precious, might be worth a 2 second safety back up. Even if you have experience and good technique, 3 cents worth of tape to assure your vintage part is undamaged seems like a good bargain. Will I do it next time I remove a stem? Who knows, (probably not) but I appreciate the simplicity and effectiveness