I have one cold radiator and I suspect the value pin is stuck but I can't see how to remove the thermosatic value cover to get to it. Its a Danfoss make and has some sort of spring mechanism which keeps it in place. I've tried twisting, pulling in various ways but cannot see how to remove it. There's no holding screw as far as I can see (but it's a bit inaccessible). I'm worried I'm going to break it if I continue wrestling with it. Does anyone know if there is a particular way to remove it?