High demand isn't the only thing keeping the Apple (AAPL) Watch from successful deliveries to customers. A critical component of the watch made by one of two suppliers is found to be defective. This is according to a report by The Wall Street Journal. The key part in question is the watch's taptic engine, which causes the device to vibrate or 'tap' users whenever they receive alerts or notifications. Taptic engines specifically manufactured by Chinese components maker AAC Technologies was found to 'break down over time.' Apple responded by scrapping the watches with the defective parts from its shipping queue. The company also shifted all of its taptic engine orders to its second supplier, Japan-based Nidec Corporation. Apple said in a statement 'We know many customers are still facing long lead times and we appreciate their patience.'