So the set screws that tie the shaft into the transmission coupling on my little perkins and the transmission seem to have a special joy in working themselves loose. *When I first bought the boat they literally came all the way out. *I keep a constant eye on them now and they keep coming loose. *There are 2 of them and have a small hole bored through the side of their square heads. *Isn't a wire band often put through that and "tie" them together that way? *I am thinking doing that and setting them with some locktite will help keep them from doing this? *