I discovered that the thermistor should read around 26kohms at room temperature - mine is 24k. I cleaned the contacts in the small black connector and the thermistor pins, now I don't get the F13 error (unless I remove the connector - then I do).
This suggests to me that the PCB is probably ok (?), but the overheat trip switch still cuts off the element power.
The small black connector and wires on the thermistor look ok.
Do you think the thermostat is faulty?
Would you know what resistance it signals the PCB to switch off? Then I could test it.