I have the big brother of yours but the controls are the same. Just open her up clean the contacts as recommended above.

Also the thermostat can be recalibrated. I did mine using a laser thermometer. Once the temp reaches your desired amt turn the screw responsabe for the bimetal to shut the heater off. Back it off till the neon light goes off.

From now on when you set the dial to that temp, you will be sure it will be correct. Just be aware most of these type bimetal thermos are never accurate so be sure to chehk the temp regardless.