I've got a Fisher and Paykel fridge freezer model E240B but the
thermostat isn't working. The motor runs continuously and eventually
even the fridge compartment freezes up. I've taken the thermostat to
pieces as much as I can. The adjustment knob connects to a 1K
potentiometer that is working fine. Tucked behind the cooling plate are 3
sensors of some sort. One black one about 20 mm long. Is this the
thermocouple? The other 2 are discs about 10 mm diameter. I thought at
the start that they might be magnetic designed to stick to the back of
the cooling plate but they aren't magnetic. Has anybody any idea what
might be wrong. How can I test these components? What are they?

Photos he-
https://ibb.co/dcCyqPt
https://ibb.co/pLwnRHm

Thanks.