Are you having trouble with stemware slipping from the chuck? Try this cut a small piece of a rubber backed mouse pad and and glue it to the tip of the chuck jaws leaving about a 1 mm space between the piece and the back of the jaw (rubber side up).. This will force the base of the stemware  to the back of the chuck and hold it firmly. Works great for me.

Also if you do not have the rotary accessory tool. GET IT. You can level the stemware in seconds.