my kiekaefer shifter lever effort is getting stiff on port engine
other engine is almost effortless with a slow motion.

what maintenance should be done or what wears out.
is it typical for cables or could it be the drive linkage itself.
1988 bravos on formula with 380 hrs.

Remove the lower shift cable that is attached to the shift-plate on the inside of the starboard manifold. This cable runs through the transom to the outdrive. Push and pull the inner cable back and forth to see if the there is any binding. If the cable shifts easily, then the shift-cable between the control and shift-plate needs to be replaced. If you feel a lot of resistance or binding on the lower shift cable, then the lower cable should be replaced which requires pulling the outdrive and feeding a new cable in through the transom. This is the most probable solution. And like you suggested, it may be the linkage in the lower unit.