Hello, The upper swing bearing does not hold up on my old d100. the bearing breaks up and falls apart. The bearing has a rounded outter race and is about 3-4 inches in diameter. Now, after replacing the bearing twice. The bracket or yoke that holds the bearing is damaged.Any ideas on how I can make this weak point stronger. Modify with a roller bearing? Do I measure the king pin for size etc. Otherwise its still a great little machine.Thanks scott