Open up the old chuck all the way and there is a screw down in the middle of the chuck, unless it is missing. The screw is left-handed threads. Remove the screw. Take a large allen wrench. Tighten down in the old chuck. The chuck is right handed threads. Lay the tool down on its side. Take a hammer and hit the other end of the allen wrench several times until the chuck comes off (some of them are on very tight). If it doesn't come off, then spray WD-40 down inside the chuck and let it sit overnight or for a few hours and then try it again.
Good luck!
Don- www.toolsandmachinery.com, February 2009
