Speedoo oh no...

[andyall]

Hi i have a speedo problem, it tends to work then not for a few mins at a time (all other gauges are fine) until the engine is up to temp then it seems mainly ok so just a few questions , i have read other threads but they were not conclusive.
1) Would i be right in thinking that it works better when its warm because the heat would affect the sensor and give it a better connection ( metal expands when hot) ?
2) On a 2000 plate 2.0 hdi 406 is the speed sensor located on the back of the gear box just to the rear of the bottom center eng mount or is there another one somewhere else?
I Did have this problem 6 months ago but took the sensor on the back of the gearbox out and cleaned both the sensor and the plug that attaches to it, (someone told me this was the speed sensor) this seem to do the trick at the time but removed it today and did the same but this time no improvement, im guessing maybe its giving up now? Any opinions or answers gratefully received, thanks