Mitsubishi 520 control.....Problem is that the end of a threading move, the Z axis stops and the X remains in the work for at least one revolution before pulling out, washing out the last thread. Not a problem when threading into clearance but otherwise makes a nasty looking thread end. Program has been checked and double checked (even by Daewoo). Parameters seem to be right. This was bought new and has always done this but now we can't tolerate this on parts we are making. Any ideas?