Help! I have an old Osborne strap cutter that won't (or I can't) let me cut an even strap (5/16 to 1/2 inch wide). When I start pulling the leather through the strap cutter the piece of leather has a tendency to pull away from the body of the strap cutter. The blade measured from the sharpened edge to the body is narrower ( around 1/16 of an inch different) than the back edge of the blade to the body. Should the blade be parallel to the body or slightly wider at the edge, than at the back edge of the blade? Do I need to file the opening in the body, so that the bar will allow the blade to sit parallel to the body? The blade has a taper from front to back, that looks like it was ground that way at the factory, and contributes some of the difference between the distances from the edge of the blade and the back of the blade. Thank you for any help, you might give me.