We have the first series of the Duet front loader Washer/dryer. The washing machine shakes the house across the horizontal axis of the house. It is similar to an earthquake. I bought vibration dampening feet, which initially helped (the machine is on our 3rd floor level of the house). The machine is level. I read in another post to lower the feet as close as possible to the floor (not extended). The machine does not move across the floor, it shakes after it starts the slow spinning cycle, it usually stops as it gets to full speed.
I was told by the dealer that they have better dampening now than when they first came out with these machines. He also said to try to cut a square piece of 3/4"-1" plywood and screw it down into the floor joists, then mount the washing machine to the floor, but not to the side walls of the room.
Some suggest to evenly load the clothes, but you don't have control over the balance of a front loader like you do a top loader.
If anyone has any other suggestions, please help, I getting dizzy.