Bad transmission, if the washer is under 10 years old it may have a ten year trans warranty so a free part could be had. However the labor charges will still make this a very expensive and sometimes difficult repair and one I would not generally NOT recommend to our customers. We did this exact repair for a customer about two months ago, the washer was in a basement where the area had been remolded in a way where the machine could not be removed without cutting out two door frames, so we fixed the machine and even with a free transmission the repair cost nearly $500 for a washer that was not all that great to begin with.