On the z axis gib adjustment should I be able to tighten it so it is hard to move the head. I have tried adjusting it but cannot seem to get it tight. I have removed the lower gib adjustment screw and the gib slide half way out. . When I loosen the head locking levers the DRO shows a movement about 20 thousandths. No matter how I adjust the gib adjustment screws I cannot get rid of this movement. Has anyone else had this problem. Could I possibly add a shim. Who would be a good person to contact a Quality machine tools about this.