While the switch itself may be failing

It is technically identical to the Honeywell 4074ELR/U

use 22 AWG or larger twisted-pair wire and keep the run as short as possible to minimize resistance-induced temperature offsets

but the technical specifications and hardware are identical

Operational Efficiency: Eliminates the need for off-site testing

Johnson Controls T-2100-205 Thermometer 30067439-890 While the switch itself mayJohnson Controls T 2100 205 Dial Thermometer, 40 to 240 Degree Temperature Scale, "B" Bulb Element, Flush Panel Mount, 15' Capillary Length, Stainless Steel Case, Vapor Filled Copper Element, "B" Style Elements Require a Minimum Insertion Length of 9 1 2"