Ariston OS-KVE160L intermittant cooling

Ariston OS-KVE160L intermittant cooling

This built-in under the counter fridge has worked great for 10 years. We noticed it luke warm the other day, so moved all the food to our bigger US style fridge freezer.
I’m trying to work out what’s wrong, so have removed the thermostat and am trying to see if it’s working ok. I read on the FAQ section that these rarely go wrong.

Anyway, I’m not sure how to test it, I noticed that the unit had two brown (live?) terminals, so figured maybe the resistance is presented between the two (seemed a good place to start). With no power (unit removed) I measured 2.2 Ohms between the terminals. When I heated the trailing wire with a hairdryer, this dropped steadily to 1.3 Ohms, and when I cooled it with an ice cube, it rose to 2.3 Ohms (at which point I stopped).
Does this mean that it’s working ok? It appears so, but I’m hoping I’m wrong. It seems such a small resistance, and I’m sure I was reading the scale correctly on the multimeter.

Thermostats for this fridge are only £26 from this site, so it would have been a cheap and easy repair.

If I’m right, is it likely to be the control board instead? If so, any ideas how I get to it, and where can I buy a new one?

EDIT – The fridge does still cool sometimes. If I open the door every 3 or 4 hours, sometimes it’s cold, and other times lukewarm.

Thanks in advance for any info offered.