Replace the thermometer

Take the thermometer out and fit a new one

From Kamado Joe's 2012 guide (Classic I), which uses the same kind of nut; no Joe Jr. method is published.

1. With the grill cold, open the dome.
2. Find the hex nut on the stem inside the dome.
3. Hold the dial outside and undo the nut inside.
4. Push the new KJ-T13 through the hole from outside.
5. Tighten the nut snug with the dial upright: "do not over tighten".
6. Check it in boiling water.