1980 DT140 shift cable...neutral and forward or reverse not both

Ok team. Need some help here. Have just replaced lower unit on my DT140. Before replacement the gear shift was operating normally. Now there is only enough travel in the clutch lever where shift cable selects to change from forward to neutral or neutral to reverse but not full range of forward to reverse. If I remove the cable and move the clutch lever next to power head by hand I can engage forward, reverse and neutral. It is like the cable does not have enought travel to move the shift lever through the full motion. My mechanic says get a new outboard ...I completely get that it's getting long in the tooth but apart from gear selection it's running great and is only used in fresh lakes for towing kids. Anyway, has anyone had this problem before. Do not want to replace the clutch cable as I am not convinced this will give any more travel on the clutch lever. Thanks for reading. Rick