Peter, not strictly true. There are two switches as you say - one is a thermostat and the other a thermal cut out switch.
To check if these are broken, you need to remove the retaining screw and feel the diaphram - if this is concave (feels pushed in) the thermostat is knacked. Same applies to the thermal switch. If the diaphram is loose and convex, the unit is fine.
Given these little items cost between £10 and £20 each, worth checking before you throw £20 away.... When you're looking to replace thermostat, check for green spot or not. Two models available dependant on age of machine.
To avoid probs with your thermostat, always make sure you allow the drier to complete the full cycle - loads of people pull the laundry out as soon as the cool cycle begins. This will reduce the life of your thermostat over time...
Learned from experience - & wife paid for the spares as aversion therapy!!
Paul Sale
September 2006