Hi, guys.
My Disco 300 Tdi's temp gauge has started playing up.

It takes ages to move off its starting position and only gets to just above "C" where it moves around quite a bit.

I have changed the thermostat but no change to the readings.

Sender unit duff?
Poor earth?
Is there a voltage regulator for the IP dials like on REALLY old cars I have had in the past?

Any further lines for investigation gratefully received.

Cheers.