I can't speak to the specific model or manufacturer, but older ranges do typically use a thermocouple, which is a sensor that sits in the path of a pilot light. It's there to confirm that the pilot light is on to ensure that when gas is released, it will have a flame. If the light is off, the thermocouple won't let the gas turn on, for safety reasons. This technology has largely been replaced by electronic ignition - the mechanism responsible for the clicking sound when you turn on a range. And yes, thermocouples do sometimes wear out and need to be replaced. You also find thermocouples in gas-fired furnaces and water heaters.