Hello, The house that I live in is brand new, only about 4 years old. Everything is new. Lately , I have noticed that the toilet in on the second floor makes loud "thud" noise and gushing water sound. You can hear it in the walls. But it does not do this all the time. Maybe once or twice a day. Help!

I have noticed that the toilet in on the second floor makes loud "thud" noise and gushing water sound.
Do you hear the noise as the flush goes down or as the tank fills?
If the noise is when the tank fills which ballcock is yours? Regards, Tom