I am replacing a broken cover in my in-ground spa (spa is 20 years old and covers have been replaced at least once previously a while ago). I bought a Hayward wgx1048E replacement cover. When I remove the old cover there is a flap that folds down and blocks the drain outlet if the cover is removed. The new cover does not have the "arms" underneath the cover to hold the flap open when the cover is in place. Do I need a new insert for the drain or did I by the wrong cover? Thanks.