I would use an ohm meter. Disconnect your power and isolate yout stat from your element. Then put an ohm meter on your stat leads and adjust your stat up and down. The ohm meter will show an open or close reading as you do this if it's working. If it shows an open condition no matter where you set the stat, your stat is most likely bad. It it seems to be working you can also use the ohm meter to test the element. Read the element leads coming off the element. You should read some resistence with the ohm meter. (how much will depend on heater wattage) If you read no resistence the element is either burned out or may have a safety switch or fuse in line somewhere that is creating an open circuit.
