You cannot shoot a certain area in the screen.
-Check to see the monitor's purity with red, blue, green, and white screen in the "COLOR CHECK" in the Manual Test. If you find purity problems, you should degauss the monitor.
-Check to see there is no magnetic equipment around the cabinet. This may also cause the monitor to become magnetized .
-After degaussing the monitor, you can check the gun and monitor in the "GUN CHECK" in the Manual Test.