Originally Posted by madpogue

Yeah now I see, that's an extension of the cable further forward. Good news that it shifts; that probably means your whole issue is with the cable.

To the best of my knowledge, that cable is a hack; all the SA cables I've seen are pre-built with the ends attached directly. I would bet the cable broke at some time, and someone hacked in a generic cable, and used that screw and nut and L-shaped piece at the right end of the photo (toward the front) to attach the threaded barrel end of the cable. McGuyver meets Rube Goldberg. You could see if adjusting the barrel will take the slack out of the cable, but you may need to adjust how/where it's hacked together (just outside the frame of the photo).