Tip From the Archives
You are moving your head as you putt.
A very small amount of rocking or head movement in the direction the putter is moving is okay due to eye dominance issues. Do not allow your head to move too much; it will cause you to move your spine and shoulders for a mishit. It is more important that the center of your neck and hips remain centered throughout the entire putt.
Practice putting at dawn or dusk while the shadows are long or you can create your own shadows indoors. Set up to the ball so you can easily see the shadow of your head. Watch your shadow to make sure you are not lifting your head up or making any excessive head movements during your stroke. Do not worry about making the putt at this time, simply focus on making a smooth stroke while keeping your neck and hips in the same location.