I know this is old but..
There are shipping bolts that need to be removed from the back before using.
+1
I was thinking both those thoughts.
I installed my daughter's new washer dryer for her. ON the back, the tubes were wrapped around some screwed in 'thing'. It said to remove the 'thing' and un wrap the tubes. Being more macho than the manufacturer, I unwrapped the tubes without disturbing the screwed in 'thing'.
My daughter's machine danced around the kitchen and made a racket.
Something fell against the washing machine door and bent the window, so they called for a repair guy. They also asked him about the movement and noise. He checked the back and unscrewed the 'thing'. He said it was quite common for people to mistakenly leave it screwed in. If it stays in through too many washes is could break the rotation system.