Diplomat ADP8132 not heating

Hi we have a Diplomat ADP8132. It appears to have gradually stopped heating the water, and now now longer heats at all, and therefore on the non-timed cycles goes on forever.

I’ve read all the posts I could find about this so I have done the following:

1. continuity checked the heating element (is fine)
2. checked the PCB for obvious flaws (seems fine)
3. pressed the thermostat reset, but it didn’t click

My question is (before I take the machine out of the kitchen bench and remove the thermostat to check it)in your experience how likely is it the thermostat itself has gone? How do I go about testing it, is it a simple continuity test?