1. First, the broken end is heated on a gas stove with a slight fire, which is about 2 mm long, and the processing area is prepared to be dark red, and then the temperature is slowly lowered away from the flame, so that the spring material at this place is annealed and softened.

2. Secondly, heat the original heated area on the fire until it is dark red, and then quickly leave the flame for rapid cooling to harden the material.

3. Just put the clockwork back at last.