I also have 2 Wickes trvs sticking closed (from Wickes about 3 years ago). The pins in the valve body move freely, but the plungers in the heads are fully extended regardless of temp setting. I am sure my problems are with the valve heads, but can they be dismantled/fixed? I can't find exact replacements, and would rather not drain the system (or try to freeze the pipes).
Fergus, January 2008