I thought my starboard flybridge shifter cable needed replacing. When I began tracking down the problem, taking controls apart, using Jeff's compressed air lubricating technique and several additional ideas, I found the problem. A wire bundle in the lower helm had worked it's way behind the shifter bell crank and blocked the mechanisim. All is well in shifter land. Thought my discovery might be helpful to others.
Jim
Jim Hemphill
Detour
'87 32' FBS, USCG Certification #1057921
Berthed MM 207 Tennessee River, Picwick State Park Marina