you probably have a sock or something similar gone down, not an easy one to sort for a diy job but put a socket on the pulley wheel nut and try ratchet it clockwise/anticlockwise,figure out where the obstruction is (normally front of drum) and try fishing it out with a wire clothes hanger, open it out and put a hook on one end, if its under the drum removing the heater element is usually the easiest route, if you get it out fit a new rubber gasket as they have normally distorted allowing this to happen
keymatic, February 2012