My particle counters touch screen is not responding properly. Many of our particle counters viable samplers and even the car air pro have a built in screen calibration. Performing the screen calibration is simple.  With the unit powered off hold the touch screen with one finger Power on the unit The unit will prompt you to perform the screen calibration Follow the on screen instructions Once complete cycle the power on your instrument  This is how you perform a screen calibration on many of our instruments. If this method does not work please contact out technical support team to run you through more trouble shooting steps.