Miele G646SC dish/wash does not heat?

The wash water does not get hot and there is no heat to dry the dishes at the end of the cycle.
The flow through heater shows a 20 ohm resistance which I calculate is about right for 3kW heater.
I have changed the heater relay and also the stainless steel thermostat mounted in the sump (albeit with secondhand bits bought off the internet) The thermostat has a resistance of 8000ohms reducing to 3500ohms in almost boiling water. At the time in the cycle that you would expect the heater to be on there is no voltage upstream of the overheat thermostats on the heater
Any ideas