THE CLOCK MOVEMENT IS HELD IN PLACE BY A PLASTIC SLEEVE.  TO REMOVE THE MOVEMENT, PUSH IT OUT FROM INSIDE THE HELMET.  TO REPLACE THE MOVEMENT, PUSH IT BACK IN.  THE HELMET IS HOLLOW WITH AN OPENING ON THE UNDERSIDE. 

NOTE:  THE CLOCK IS WRAPPED TIGHTLY IN BUBBLE WRAP AND TAPE.  I HAVE CUT OPEN THE WRAPPING TO ENSURE THE CLOCK IS WORKING PROPERLY.