Originally Posted by Ericb760
Mine has hose clamp that attaches the valve to the drain pipe. You can see the metal band in this pic. They are made to be replaceable. I assume yours is the same. Maybe removing the whole valve will make it easier to work on getting it closed.
Rubber gloves and (I think) an 8mm box end wrench will loosen the 4 retaining nuts. As you loosen them all, try the knife valve. If it is still frozen, remove the whole shebang, and clean, then spray with PAM or similar silicone product.