I would loosen the cable ends and pull the cable out as far as I could and
spray "blaster" down into the outer housing.
Do the same on the other end. By hand, run the cable in and out until it loosens up.
If that doesn't do it, I carefully notch the outer housing (don't cut the inner cable) in about the middle and spray blaster in both directions from
the notch.-Bob
Let us know how you solved it.