Hello. We also have one of these, with the same fault. It has happened to us before. You can start by checking the thermostats and heater elements. At the back of the machine you take off the plastic central cover (2 screws) then the heater cover panel (about 8 screws) which goes from the centre to the bottom left corner. There are also 2 small screws in this cover that allow the heater and thermostat piece to come free.
There are three "button like" things on the top of this part. The outer two are thermostats. If you have an electrial meter you can check if they conduct current or not. If they conduct then they are working if not then this stops the heater working. One of them has a small hole in it. If you push a pin in here it can reset the thermostat, check again electrically.
If none of this proves to be the fault then have a look at the four heater elements. Can you see if there is any breakage in the heating coils. If you can then check for electrical conductivity.
Thermostats and heaters can be replaced, easy fix.
If after that you have still not found the problem then you are in my position now. I would welcome any help!
Regards Steve 01625 500970, call me if you need.
Steve Nixon
January 2010