Usually the diaphragm on the top of the flushing valve needs to be replaced . The reason being the rubber diaphragm worn out as times go by.It is not holding properly , that's why it hums and vibrate.
You have to loosen the four screws that were holding the cover down on top of the flush valve.
This replacement rubber cost only a few dollars,when compare to replace the whole flush-valve.
You have to loosen the four screws that were holding the cover down on top of the flush valve.
This replacement rubber cost only a few dollars,when compare to replace the whole flush-valve.