New Parts needed for this step:
Each crank has a slotted socket at one end. The cranks are installed on the crank gear shaft using this socket.
Once installed, the cranks should rotate downwards. Thanks gravity.
If the cranks do not rotate freely, check to ensure no gears are interlocked. Also ensure the weight shaft key is still centered in the weight gear. Until all pieces are installed, some have a tendency to shift out of alignment.