You may get better advice specific to the H-18, but most of the H-16 sailors I know (including myself) just remove the set screw. The adjustable bar in the upper casting controls how far back the rudder go, which is what's most important. I guess the thinking is that, while underway at least, the rudder will be pushed back and there's no need to limit it's forward range.....not much room for slop there anyway. I'd recommend you get rid of the set screw after making the repair and see how it goes.....you can always put it back later.