The problem is there is less than 1/32" between the bottom of the threads and the inside diameter of the thread gauge ring, probably just under 1/64" that is the only thing holding the threads together so very little tightening force is required to loosen the steps. The threaded part has a 1/4-20 loose fit. The probe is 0.15 inch in diameter and hangs in a threaded ring. The spec for the smaller thread diameter for 1/4-20 is .210", although this gauge is even smaller as it fits loosely.
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