No doubt, this question has been asked and answered previously but I did not see it. My husband just finished installing a new Toto Drake toilet. All went well but we cannot get the flush adjusted. The tank does not empty completely - the flapper closes too soon. He has repeatedly adjusted the chain, shortening the slack as suggested. If he takes up any more, it won't reach. Any suggestions on what else to do? We are assuming the the tank is supposed to pretty much empty of water when flushing. Maybe not??? Thanks, Sharon