How do I level my washing machine properly?

Your washer must be installed on a solid, level surface to prevent excess vibration during spinning. Use a bubble level to check that the top of the washer is level both side-to-side and front-to-rear. Adjust the washer feet as needed by having someone lift the washer slightly while you turn the grey plastic foot to extend it downward. Once level, use a 17mm wrench to tighten the locknut against the washer bottom to lock each foot in place. Press down on each corner to ensure the washer doesn't wobble and all four feet press equally against the floor.