I have a 1990 Johnson O/B 120hp VRO. The engine runs great but just recently started have a problem with the gears. I shift engine out of fwd or rev into neutral and then shut off. Sometimes when I start engine again it is in gear eventhough the shift is locked in neutral. I'm not even sure how the engine starts with the boat already in gear. I need to jiggle the shifter alot to get it into neutral. Is the problem linkage, the cable or the lower unit? Thanks.