Bosch Classixx Tumble Dryer Not Getting Hot?

Folks,

I've had the back off and looked for the reset button and can't find it. It's at least ten years old with a rectangular door. There appears to be some sort of sensor in the top of a black plastic, wide diameter fitting which is connected to the vent hose. It has two maybe three wires coming out of it but they appear to head back towards the main rotary selector but I cant be sure as I'm looking underneath the drum from the back and this sensor is at front of the machine. Alas no reset switch. Can anyone help?

Thanks

Steve H