Give them plenty of exercise and keep a snack in your pocket for when you call them.
About gunshy, I broke one once using the progressive louder noises method at feeding time.
[clap hands, bang feed pan, slap a flat piece of wood on something flat, bb gun, 22 rifle)
I heard a man say he broke one by tying it out and then shooting a box of shells (target practice) from about 50 yards away. Then give the dog a snack and put it up.
Repeat this a few times, each time getting closer. Don't pay any attention to the dog while doing this.
Like he said: what have you got to loose?
Calling the old dog, like Jake said, shock collar.