Product review (5 stars): Good product, probably never needs replacement unless there is physical damage.
This is not a part that should ever go bad. It has no moving parts and relies on conductivity to function. Unless there is physical damage like a crack or oxidation, it should never need replacement. The two bars act like an open switch until wet clothes touch both bars and closes the circuit. That's how it tells when clothes are dry, no magic here.

I replaced both of mine precautionary (and unnecessarily) as part of a high limit Thermostat replacement. The high limit Thermostat fixed my problem with the clothes not drying and the dryer not being very hot.