JD,

Did this happen all of a sudden, or progressively worse as time past ?

First check and make sure the washer is level, the rear self adjusting,levelling rear feet are locked in place( raise the rear of the washer a few inches of the floor and let it fall back down).

You'll need to remove the washer cabinet, and check the suspension springs and slide plates for excessive wear and tear, or loose/missing springs,etc.

You didn't mention if there any strange noises,

Here's some help for you to access the inside components and suspension parts :

1. Remove
the two Phillips-head screws securing the front corners of the console to the washer top( these 2 screws could also be located on the back side of the control panel end caps, under the decorator trim strips on the front of the control panel) panel.
2. Tip the console back on the hinges that secure the top of the console to the washer back.
Components inside the washer cabinet can be accessed by completely removing the outer cabinet as one unit.
1. Remove the console mounting screws and tilt the console into the service position.
2. Unplug the lid switch harness connector from the receptacle in the washer top.
3. Remove the cabinet mounting clips by placing the flat blade of a screwdriver in the clip.
4. Remove the cabinet by tilting it forward and pulling it away from the washer.
5. The rear panel can be tilted back for additional access to components at rear.

Good Luck,
:) :) :)