One noise source is the drain pump hub assembly built into the pump pulley. I believe it is a slip clutch built into the pulley to deal with objects that might jam the pump. It contains a corrugated metal ring that slowly works its way upward out of the hub until it begins to touch the metal plate that forms the bottom of the pump. At that point it makes a terrible racket. You can work it back into place with a screwdriver, even without disconnecting the hoses. Just remove the belt and the three screws holding the pump in place. Tip it up and you can see the corrugated ring touching the bottom plate. Carefully pry between the pump base and the top of the ring as you turn the shaft. Move it a little at a time, and you can get it back into its original location with the top of the ring flush with the top of the pulley. You may want to tap on the bottom of the pulley to put the shaft back into its original position so the shaft turns freely. The problem will reoccur in a few years, but the fix is the same and the price is right: zero.