Help please

hi, I have an issue, on the pierburg 2e carburettor there is a wire going to the ptc heating element, for some reason this wire gets extremely hot, I mean so hot that once you touch it, it melts your skin, this only happens when the ignition is on or the car is started and running, it will only cool down once the car is switched off and key removed.

Does anyone know what could be causing this issue? 

I've checked the haynes manual and that tells me that the ptc heating element runs off a single 12v positive feed.

sounds like the heater is duff and drawing too much current, or it may be the earth point is poor on the carb so check that while you're there. its the brown wire from carb to rocker cover bolt

Cleaned up the earth points, still no joy. 

Anyone know where I can source a ptc heating element for a pierburg 2e carburettor?