Thanks Mr. Force, our belt cover rubbed on the bottom pulley. We bent it a little and that solved that issue. The loud rattle seems to come from the auger. It's two pieces that just rest on each other. The vibration from the machine running causes it to rattle. Starting the cutters causes it to scream. When you fill the hopper with seed the problem is solved. When the seed hopper gets low the rattling starts again. I am thinking about job welding it together. But if something would break I would have a hard time taking the unit apart. They should have just put a few bolts through the two pieces and they would not have any issues.