Many times moisture attacks the hexagon shaft that the friction disc assembly slides on. It slides from side to side on the shaft to create Reverse 1 & 2, and the other end creates 1-6 forward. With a wire brush and sandpaper, clean the rust from the hexagon shaft, at the same time lubricate the friction disc bearing with penetrating oil and with a soft hammer, tap gently until the assembly starts to slide on the hexagon shaft. After all the rust is removed and disc assembly is sliding, apply a light film of graphite grease on the shaft. You may want to re-lubricate on a yearly basis.

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