I have replaced three belts in 2105 miles! The reason for replacement is jerky low speed launch. The new belt always has corrected that symptom. The replaced belts are like new condition except for the glazed sides. I now am faced with the prospect of replacing another (this one only has 50 miles). I have been attentive to proper break in procedures. I wonder if there is a benefit to sanding the belt sides or pulley?