Hi Alastair, failure 1 is an NTC break.That is the temperature sensor in the base.If you take the front metal plate off (4 torx screws) You will see the sensor at the front,it has 2 blue wires connected.This part is called a feeler and is approx £30 plus vat and postage.
tel 08457 959722
You just twist quarter turn and pull,taking off wiring plug later.All the best.
Foxy
August 2008