1. To replace the NIST sensor, first unscrew the cap or old sensor from Port 1 on the Node.
2. Next line up the arrow on Port 1 with the arrow on the NIST sensor and carefully screw in the sensor so as not to damage the pins. Don't force it and do not remove the calibration tag attached to the sensor.
3. Take the original NIST that was removed and discard.
4. Place the sensor back inside your fridge or freezer.