Following sprung-mouting instruction, they move middle of center toward 1/4" inch, do you know why? i can't understand. please advise. ---------sprung mouting instruction-------------- 1) Find something that shows up on the sole and mark the center of the toe and heel on the sole. Check the boot and sole to best find the center spots. 2) Draw a line from the toe spot to the heel spot. 3) Find the center of the line on the sole between the end edges of the sole and mark it. 4) Measure 1/4" toward the heel from the center point and mark this point with a line across the sole at 90 degrees to the center line. 5) Align the frame with the center of the toe mount and heel mount on the center line, and the horizontal cross member in the center of the frame lined up with the horizontal line on the sole (# 4). 6 Drill the holes through the frame (you can drill inward a little to avoid hitting the frame with the drill, and they will mount easier because of the slight angle). Or mark the mount holes through the frame and drill with the frame removed. 7) ENJOY