Most SCT touchscreen problems (excluding physical damage) are caused by incorrect integration of the sensor.
Assuming that the touchscreen has been correctly calibrated, this fault may be due to the close proximity of metalwork to the touchscreen.
As the surface capacitive touchscreen relies on grounding via the user’s finger to indicate a touch, placing a metal bezel directly onto the touchscreen glass surface is, in effect, grounding the touchscreen around its entire perimeter. This will cause the touchscreen to under-perform.
In addition, if the touchscreen and monitor are mounted on the machine chassis and the door opens and closes onto the touch sensor, the opening and closing action will also have an adverse effect on accuracy.