First, is the frame level? Raking with the frame not level pushes the rake teeth away from their optimum “angle of attack”, causing them to push up rather than be pulled back as the rake moves over the ground, resulting in a “hop”. An improperly leveled frame also reduces the way the rake teeth vibrate and diminishes the rake’s screening action. Rake teeth are made curved to enable the tip of the tooth to lead the base of the tooth and maintain ground contact. The tip of the rake tooth where it touches the ground should NEVER be vertical to the ground, or it will negate this curvature. The tip should be running ahead of the base, not vertical or behind it. Proper tooth orientation is illustrated below.
Level, Not Level
Second, is the center pin as tight as possible? The nut on the center pin should be drawn up as tight as possible and then backed off just enough to get the cotter pin into the nearest of the two holes. When the unit is brand new the paint in this area may make it difficult to angle, liberally greasing this area will make it work easier. Retighten the nut after a couple of hours during the initial use. Keeping the center pin tight eliminates any “slop” and keeps the rake level with the frame and on the ground.