The front motor adjustor on my 470 seems to be either missing parts, or assembled incorrectly, causing the motor to move up about 1/8". On the top of the assembly, where the bolt protrudes, I have a steel collar roughly 1" long, sitting over the bolt, and a 3/16" fibre washer which slides over the collar, followed by a steel washer and nut. When I tighten the nut, the collar prevents the washers from going down far enough, leaving said space. What am I missing? A link to an exploded view would be an enormous help.