My Dawes air-fuel ration meter (the 4 LED one) started playing up a while ago, gradually indicating a weaker mixture on full throttle. Eventually it stopped working at all. Obviously I checked the mixture by other means and it is fine - even had a remap.
I had a universal lambda fitted and, although the engine was running OK, I got a Scooby one and it is still the same.
I checked the meter by touching a 12v source to the sense lead (as recommended by Dawes) and this indicated the meter was working - lights up the blue LED.
I checked the voltage out of the lambda and it is only about 0.05V at idle, it should be around 0.5 so this must be why the Dawes does not light up. But the car runs fine and it even passed MOT in this state.

Anyone got any ideas?