When 150 workers at Foxconn climbed to the roof of one of its factories in the central Chinese city of Wuhan in a labour dispute earlier this month, it was a chilling reminder of the suicide series that shook the world’s largest contract electronics manufacturer less than two years ago.

There were no suicides in Wuhan on January 3, and workers present that day said no one was actually threatening to jump. But the drastic protest reflects new labour woes plaguing the company which makes the lion’s share of the world’s iPhones, iPads and other electronic gadgets.

Analysts say Foxconn’s move to transfer mass production of many gadgets from one mega-plant in Shenzhen, the export manufacturing hub next to Hong Kong, to new large plants in inland provinces has created a more complex wage structure and bottlenecks that trigger disputes.