I just replaced a gray tank valve for my kitchen tank, the coroplast was notched around the spring hanger and drain pipe coming, I just extended the cut for the drain pipe to give me room to get to the valve. I wasn't careful enough reassembling the new valve and pinched one of the O rings. Good thing I had purchased 2 valves, robbed the O rings from the spare valve and went through the install again with success on the second try.