How do I correctly adjust the sight on a lever action rifle, front or rear sight?

I recently bought a Marlin 1894 in .357 magnum, and it came complete with a sight which is out. I've had it at the range, and it is putting patterns to the right a little. 2 range officers confirmed this. My dilemma is this. One of the range officers told me to move the front sight (to the right) with my hand somehow? It is a standard screw in front sight so I don't think it could be tapped? He also said quite adamantly, not to dare go touching the rear sight! However, the manual says to tap the rear sight to adjust windage. Does anyone know why he would say this? I should also point out that on inspection, it looks to me that the rear sight is slightly misaligned to the right, so i'm tempted to tap it to the left, with a brass taper of course. Can anyone enlighten me?