The plastic thing at the bottom with the clear tube is the pressure switch, when the water reaches a certain hight it puts pressure down the tube to switch the dishwasher to continue the cycle.
The thermostat is at the bottom towards the back, it is black and silver with 2 wires on it, it is attached through the floor of the machine and is probally attached to you element somehow. This is a common problem with this design, and its difficult to get spares
Andrew, November 2010