After some effort and no obvious way to get to the heater and what i now know from your web site to be the NTS sensor i eventually took dishwasher to pieces and have pump, heater, ntc sensor on the workbench (having made diagrams of electrical connections its necessary to disconnect) this model definately not user friendly to access the working bits. Does MTC sensor serve as a thermostat?. With electrical test meter unit shows open circuit across terminals when at room temperature and in boiling water whereas heater elements show good continuity and appear good with no scale build up.