Temp Gauge showing cold all the time!

Hi
I've just bought a new Mk2 Ph1. I drove it down from brum and the temperature gauge showed cold all the way. I therefore checked the car over. Thermostat is working, fan turns on, hot air comes out of internal fan, changed the cold start sensor and the temp sensor from a running car.
Still it shows cold. I took a good look at the gauge and it does go up very slightly. My conclusion is that the actual gauge is broken inside.
I want to know if this is a common problem with the Ph1? Can I fix the same gauge by opening it up? Do I need to get a new gauge or a whole new cluster? Can anyone supply me the needed parts second hand?

the sensor wire that goes onto the gauge sensor on the side of the head its a female crimp on single wire one.


earth it to the engine gauge should fly right up if so it aint the gauge

steve

cheers. Will do that this weekend

Just a few tips. I've never opened a instrument cluster on these before. Is it all just front opening? Is there any chance of it being the actual mechanisms inside the gauge? If its just wiring it should'nt be a problem