Carberator and motor is running and idleing good, but would not shift. Outer shift cable was rusted and frayed and rubber bellows was torn apart. We have a new shift cable and rubber bellows and gasket set. Can you tell us how to repair it or give us any tips so we don't mess this up. Have been working on this boat all summer. thanks ahead for your help (1978 mercruiser 898, alpha lower unit, but top is pre-alpha?- just put on waterpump, 4barrel carb, swapped lower unit)