slacken of the jaws as if u were fitting a big drill.look down inside the center ,u will see a cross head screw.this has a left hand thread.turn clockwise to loosen and remove.chuck will now unscrew anticlockwise.i find that a pair of mole grips clamped on the end a right angles to the chuck and given a right smack usually loosens the lock.refit using threadlock.
caine, June 2008
