Have been sharpening my Stihl chain saw for a number of years, but have a problem now that I cannot solve. Recently, the saw slices to the left and getting worse [not a golfer, so don't know if left is really a slice ] after starting a perpendicular cut through a log. I have not changed the sharpening method and use a file, with a final touch by a rotary stone the same size as the file. The slice is so drastic that a cut through a 14-inch log results in a 45 degree cut at the bottom . Thought someone might have experienced this problem and have a solution so I don't have to take to professional or dealer.