Answer to "Loud knocking sound in spin cycle?"One of the braces on the back of the basket is cracked causing it to distort from being round causing the vibration and the basket to rub on the fiberglass tub wearing a hole in it (the bits and pieces on the seal when you open the door) and ultimately leaking water onto the floor.
Answer to "Loud knocking sound in spin cycle?"Its the drum smashing into the tub. Next there will be bits of the fiber glass tub and then a leak when it makes a hole in the tub. Ask me how I know!!!!!!