All ScienceWorkshop sensors with tare buttons use analog sample-and-hold tare circuitry, which may exhibit a drift in the measured value due to small leakage across the capacitor in the tare circuit.
A drift rate of less than 5-10 mV/min is considered normal. A drift in excess of this value may be the result of a defective capacitor, but is often the result of condensation on the circuit board. Storing the drifting sensor overnight with desiccant usually dramatically reduces the drift rate because it eliminates condensation that accumulates on the circuit board.
Note that the PS-2104 PASPort Force Sensor, PS-2189 High-Resolution Force Sensor, PS-2142 2-Axis Force Platform, PS-2141 PASPORT Force Platform, and PS-2162 2-Axis Magnetic Field Sensor will not exhibit significant drift because they all have digital tare circuits.
If your experiment cannot tolerate the specified level of drift in the tare circuit and you have purchased the sensor recently, please contact Teacher Support to exchange the sensor for the corresponding PASPort version.