My old American Standard external (outside-the-wall) two-handle shower faucet kept dripping, even after replacing the washers. So I replaced the brass barrel seats (the new ones have an O-ring at one end, the originals didn’t) and of course the washers. Now, if the hot water is turned-on fast, the faucet vibrates violently and loudly. Shutting the hot water and opening it slowly fixes it.
Any suggestions? thanks