Fan blade is on the end of the drum drive motor under the heater. I presume the motor is running and the drum turning? If so the blade could be loose on the shaft, if so it usually rattles on take off, if the center boss is worn you will need a new fan. to access this remove rear backpanel. If not this you must have a blockage of the internal ducting, but unlikely. Cheers
Kenjo, October 2013