Can anyone confirm its a duff thermocouple on my New World cooker please?

I have a New World Plan 6 cooker. The problem is that when I light the oven, the spark plugs keep clicking away until the oven reaches temperature. If I want to lower the temperature, I have to open the door to allow heat to escape to stop the sparking. I believe it could be the thermocouple, but confirmation and any idea of a place to get a new one.(the cooker is not that young), would be great. Thanks