An simpler way: just move the supply connection that goes to the capacitor (in this case, W & Y), to the other side of the capacitor (W & Bk). This motor is known as a 2 phase motor. The 2 windings are identical. The current through a capacitor leads the voltage by 90°, so the current (& magnetic field) in the poles of the one fed through the capacitor leads, then shifts to the poles of the other one in between, creating a spinning field which the rotor follows. If you connect the supply to the other side of the capacitor, the other winding leads and the field spins the other way. You can even put a changeover switch to switch the supply from one side of the capacitor to the other to make it reversible. If you get the leads mixed up, just measure the resistance between them. The 2 that go to the capacitor will have double the resistance between them. When you swapped the red & yellow leads, the current was only going through 1 winding L1 in Hemantha's diagram and, with only an alternating field, the motor couldn't decide which way to go.