Duo therm thermostat lost calibration

[Samflhomes]

I have 2 thermostat the main one that controls both a roof AC and the furnace lost its calibration couple years ago. It's off by 10 degrees
Think it is 80 when room temp is 70

Suddenly today my other AC thermostat in bedroom has done same thing. It was set at 75 and refused to shut off until I moved slide control to 80 and actual temperature is 70.

I do not have any Flores ant lights
I only thing I used recently was microwave

Any clues appreciated

Sam