I used my heatermeter today and had a weird temp issue. I ran to the store and when I came back the dome was at 375 and the probe, which is clipped to the thermometer, was at 135. When I disconnected it and left it outside, it was reading the air temp correctly. I know the dome temp was correct. Not sure what happened but I need to test my thermocouple. What’s the best way to do this?