NEFF D/W S4453NOGB/07 Low Heat

RE: NEFF Dishwasher S4453 NOGB/07 – runs through pgm OK, heater is OK (no earth leak or open circuit) but water temperature never gets above lukewarm. Works fine otherwise. Water level OK, circulation OK.
PCB looks fine visually – no burned connection to heater relay (the usual fault). But a lukewarm wash on all settings.

We assumed it was either the logic circuit (seemed unlikely, but would need PCB replacement) or the 4-tag NTC Sensor (like a multiple thermostat) which fits into the top of the heater housing. So we got an NTC sensor (Part 165281) but found apparently that the whole plastic sump bowl has to be detached from the base of the wash cabinet to achieve enough clearance to fit it! This makes it a major stripdown, and scarcely worth the hassle.

Is there an easier way to get this sensor fitted (it looks the same as the whole Bosch D/W range from that era)? Or is the low heat due to some other cause that we don’t know about?

Any help much appreciated. 😀

Mike Phillips