Just changed the one on me depender today and found that the wiring on the britpart replacement is different to the original. If they are the wrong way round then full tank = empty gauge and vice versa, and if the two live ones are the wrong way round then the empty light is dimmable! If the earth is on one of the wrong units the gauge only woks when the empty light is on, then nothing! Dunno if any similarities between the models?