Yes spine affects center shot. Len are you talking about the rod flexing at draw, or being under to much stress to begin with.Ive seen problems when people set them up for to much arrow pass,and have side stress, but never even really thought about the flex difference at draw.Len your cable guard answer brings up another question from me. Are there certain brands of bows that are more likely to have this problem, and what has the least amount of twist. Offset, or straight, and Carbon rods or steel.