It's not wearing out it's the physical property of all metal. Once in flex it will change it's displacement after a period of time. These wafer thermostats are all the same. Cold storage or brand new will dial in themp then three-ish days later that temp is near degree low. The metal is in use, warmed up, and been flexing for days. It relaxes and the new tempo of contraction and expansion is what will stay true for the rest of hatch and next and next. It's once you put back in storage the metal solidifies if you will. Taking out and starting up takes those days for it to be relaxed and expanding as it should under use. THat's all I was saying. It's predictable and normal. After three-ish days of use after long storage all metal wafer thermostats will drop temp as the metal is now in use and flexing differently than straight from non use.
