Just rebuilt the right flipper assembly on a EM Williams Rancho. As you can hear in the video, the buzzing is very loud when the flipper button is held. The old flipper also buzzes, but it's not nearly as loud. I was hoping the new assembly would make the buzzing less, not more. I've checked my wiring and I think everything is as it should be. I've also put the coil in with rubber washers, and made minor tweaks numerous times to reduce vibration, but nothing seems to make the buzzing go away or quiet it down at all.
Here is a link