if you can get to it and remove it then yes its easy to do... get a kettle, boil water, drop the bell end of the stat into the water and see that it opens.. if it does its ok, if it only opens a little its poop, if it doesnt open it might be that its feck or the waters to cold, in which case boil the stat in a saucepan..
you can check your rad thermostatic switch by bridging the wires on the connector to it.. this will be on the rad somewhere in most cases, this will cut the fan in, of not its fooked or the rad motor is..
check the fan by running 12v direct to it and an earth, it its not running its poop..