Originally Posted by Wampus
I also use the 12" turkey fryer thermos. I actually have 2 in mine, one about 1/2" under each cooking grate. They're cheap, easily replaced and I've found them pretty accurate.
If there is a hex fitting between the stem and the dial, they are adjustable. While the stem is in boiling water, turn the dial while holding the hex till the needle points corectly.