At lunchtime today I removed my old single part (and more expensive) ECT sensor and replaced it with the two part. The housing part from a scrapyard and the new cheaper sensor. I will know this evening if this solves my intermittent loss of signal from the sensor.
Not an easy job but worth doing, as in future you use the easier to fit and cheaper screw in sensor, and anyway you have to take the complete old unit off anyway to replace it.
TIP: Remove the heater hose from the sensor first as it will be in you way when trying to undo bottom bolt. And when both bolts are out push DOWNWARDS to remove as the clip part of the housing locates into another plastic part. The reverse for refitting.
I changed the thermostat at the same time as the gauge never went over 1/4 and now I have a correct reading of 1/2 and decent heat from a bled system.
Hope that's the end of it for a while
wait no, rocker cover gasket next lol