Besides what the other have said, I fought that with our dryer. Years of buckles, etc. left pits/chips in the dryer drum. Leaving wet clothes in the dryer resulted in stains. A new washer and dryer fixed the problem. Look for pits in your washer and don't leave wet clothes sit. If you don't have pits and remove your clothes immediately then look to what the others have suggested. Post back and let us know what you have found.