For the last three weeks, CNET has been stress testing the iPhone Duo ‘s hinge on a livestream. After over 451,000 folds, the hinge is showing signs of wear. CNET says the hinge started feeling looser at the 390,000-fold point, and by 440,300 folds, there was enough of a shift in the mechanism that the screen didn’t open in full before the machine closed it again, and there was no distinctive snap. It is 5 to 10 degrees from the fully open state and can be opened fully by hand. The wire we use to open the phone screen would withdraw before the screen was in the fully open position, but it would then sort of "coast" the rest of the way down. But between 12:30 and 1 a. m. this morning, around 440,300 folds, the screen would no longer have time to open all the way before the Fold-a-Phone caused it to close again. The ‌iPhone Duo‌ hasn’t been removed from the folding machine, and the test is continuing. CNET says the device is still operational and maintaining other screen positions, with no signs of cracking or other failure …