I just had my rebuilt 470 put back in the boat and it runs great above 1400 RPM, below that it has a clunking sound that sounds like a motor mount with no rubber insert. After investigating I found the fiber washer is above the motor mount attached to the motor not between the motor and transom mount. What does the fiber washer do and could this be where the sound is coming from. When I shut the engine off I will hear one or two loud clunks as it comes to a stop. Any thoughts would be a great help.