I had to purchase a new fuel cap for my Homelite HB25150V blower. It is a UPO4111 which according to your web page is obsolete. There are several pieces and parts included with the new cap. The internal cork gasket is not a problem, but the extra parts have me baffled somewhat. Would you explain to me how to assemble the pieces into the center of the new cap? It's all part of the venting of the gas tank. Help please...Thanks, David White