Can someone please tell me how to do this! The pin in the valve has stuck which means we have one cold radiator. The rad had been bled of air so we know that the problem is with the TRV. I am having difficulty removing the valve cover on the left side of the radiator to gain access to the pin for cleaning & greasing. The small black locking pin has been removed from the valve by the way! Thanks from a persistent lady DIYer.