Found it.
Disconnect from the mains.
Lower the door.
Remove outer cover by pushing to one side and pulling it back.Remove metal cover by taking out four self tapping screws.
You will see the thermostat facing the front , inserted into the sump.
Pull old one out, take off wire plug, put new one in and insert plug.
Replace covers in reverse order.
Bobba choo choo, June 2012