My toilet keeps making a hissing sound. I tested the flapper with red wine and within 5 minutes I had red wine leaking in the bowl,so I replaced the flapper. But my toilet still makes the hissing sound, I have tried playing with the water level in the tank and it does not help. When I lift the ball, the sound stops, however it will start back up in a few minutes. Also, when I flush the toilet there is water coming from the top of the ball cock assembly. By the way, the ball cock assembly was replaced a few months ago, but I am not sure if he replaced the entire unit, some of the tubing looks old. Or perhaps the new flapper is not provding a tight enough seal, any suggestions.