Just purchased another K60 a month ago since mine was stolen recently off my truck. The stolen one was one a couple months old. When I got my 2nd new machine the motor was shaking when I first tried to use. I discovered the belt was loose and the motor was jumping all around . Guess it was not assembled and tested correctly . I adjusted the belt tension and seems ok now. I used it a few times , then recently I hear a loose part floating around . I found this white nylon nut in the jaw housing. I disassembled the jaw housing and took it out. I looked at the parts list on line and did not see this nylon nut. I was wondering if anyone knows( Rick ) what it is or how it could have gotten in the machine. See picture.