the working parts inside are fairly simple to understand. Remove the tank lid and set it in a safe place. Look for a flap or stopper-style device connected to a chain and sitting near the bottom of the tank —
Fix a running toilet within minutes with our complete guide When water leaks from the toilet tank into the bowl, it's usually a sign of an old or damaged flapper, which is the large rubber seal at the bottom of your toilet tank. Because...
If the toilet is otherwise installed correctly, the floor is probably uneven or has cracks in it (if it is tiled). You will probably need to repair the floor and re-seat the toilet. Question Should I glue the flange to my pipe?