just as the water tank almost stops when is full,the ball valve vibrates badly,causing loud water hammm
ering!!
cleaned,and put in new valves,reduced the stop tap pressure feeding the house.

derek nixon, December 2014

When I had this problem I too thought is was the valve in the tank. Actually what stopped it was changing the mechanism in my toilet cistern.

In my case the way the toilet filled caused the pipework to vibrate making me think I had a problem with the tank. Weird I know. Worth checking yours.

Paul, December 2014