We have one of these American Standard Large Flapper that has a guide down inside the Douglas Valve to center it over the opening and it has a short old style stopper chain that connects it to the handle with a small pin and a clip. This flapper seems heavy to me but when you flush the toilet, you have to hold down the handle for a couple of seconds or it only drops about a quart of water. How can you make this large 4" flapper stay up longer so you can just push quickly on the handle and get a full flush. Any ideas? I am stumped.