How to Replace the Sensor of HK Instruments CMT Carbon Monoxide Transmitter Video
Open the housing and detach the screw terminal from the PCB but leave the PCB attached to the sensor. Unscrew the screws that hold the sensor at the bottom of the housing and replace the sensor with a new one. Attach the new sensor to the housing and the screw terminal back to its place. The device is ready to be used again.