I have an SLP tool, and I never use it. I use a straight edge long enough to go across the back of both clutches. Put the straight edge on the primary, measure the distance to the back of the secondary. Push the secondary toward the sled when measuring. It should be 5/8" (1" with electric start). You can measure both the front and rear of the secondary to determine if the clutches are parallel with each other as well. It worked as good as the tool does for me.