Wang Jin dismantles a timepiece before repairing it in their office in the Palace Museum in Beijing, April 7, 2016. [Photo/Xinhua]

As the TV documentary, Masters in the Forbidden City, becomes popular among audiences, the highly skilled and smart behind-the-scenes masters are becoming young girls' "idols". Wang Jin, 55, who has been repairing antique timepieces at Beijing's Palace Museum for 39 years, is one of them.

The repair process is quite complicated. Each timepiece first has to be photographed for the museum's records, and then a repair plan is formulated. Every piece has to be dismantled, cleaned, mended, assembled, adjusted and tested, until it functions properly. Then it goes to the warehouse for storage.

"The experience of repairing each clock is unique because you know only that it doesn't work, but you don't know why until you open it," says Wang.

Sometimes, after each repair, the timepiece still doesn't work, so Wang will dismantle all the parts and check again.