One of four toilets (Gerber mfg) in our home is very loud as it is refilling after the flush, and seems to last until the bowl is refilled. I've replaced all the parts inside the tank with the tower system vs. the ball. This toilet has been this way since the house was built 4 years ago. Builder and plumbers said they didn't think it was so bad...even after listening to it vs. the other toilets in the house...they just didn't want to deal with it. Help!