Don't pull it out until you are ready to replace it! It is a Royal pita to re-route because the hole it passes thru is not in line with where it needs to pass thru into the jet unit.
The cable is not a "serviceable" unit. That is, you can't take it apart. You can try to spray your favorite penetrating oil into the end of the cable at the shifter. At the reverse gate, that rubber bellows is a maintenance item- replace every year.
If you hear any crunching or grinding noise when you shift, your cable is shot.
There is a friction adjustment under the shifter. Have you checked that?