You sure you didnt miss a screw? There are several in the metal plate that is on the front there are 2 in the front and one on each side of the metal plate and then 2 screws that are inside the holes on the front of the muffler. That should be it. You will have to remove the bar and chain to get to the screw on that side it goes through the felling dog. Just dont forget to readjust your carb after you are done.