Problems with a component of the Apple Watch could exacerbate a shortage of the much-hyped wearable technology.
The Wall Street Journal reports that the taptic engine made by China-based AAC Technologies Holdings breaks down over time, which forced the tech giant to scrap some already-completed watches.
The taptic engine involves a small motor that alerts wearers by gently tapping them on the wrist; the technology also enables users to send their heartbeats to others.
Nidec Corp., a Japanese company that also supplied the engines to Apple, did not experience the same reliability problems. Apple reportedly shifted nearly all of that work to Nidec, but increasing its production capacity could take some time.
The news could explain reports that Apple told its suppliers to slow production of watches despite indications of insufficient inventory. The overall impact of the engines on that shortage, however, remains unclear.
Apple does not believe any of the watches distributed so far contained the faulty part and does not expect to issue a recall.
The Apple Watch, which officially went on sale last week, is the company's first new product line since the debut of the iPad some five years ago. Optimistic forecasts believe sales of the wearable could exceed $30 billion -- or 14 percent of Apple's 2015 revenue -- in its first year.