Re: How to remove
the allen screw is to lock the cable inside the shifter arm at that end of the cable, then the safety wire is attached.
You can then remove the lower shift cable housing and replace that too..
I like the extreme edition cable something like 18-2190E is the sierra number.
If you're going to replace the cable, you can also replace that end peice and the shifter arm as they can get melted and worn.
If you were having hard shifting in the water, the shift interupt circuit can be to blame.