@GroundGold First drain the toilet and shut off the water. Then lift the flapper and clean the metal edge on the inside of the tank. I think a scouring pad works best but any abrasive cloth like steel wool will do. If the problem still persists, you may need to adjust the length of the chain which connects the flapper to the pulley bar. Simply move the hook to another hole on the end of the bar (there are usually around 5 different holes to choose from). Try to keep the chain straight with just a little slack. If the chain is too tight the flapper will still leak. If it’s too loose the chain will get caught under the flapper. Hope this helps.