Stop the tiller and turn off the engine. Lift the handlebars up to pull the foot out of the ground. Look for signs of damage on the metal shaft; rocks and other solid objects in the soil can damage the foot if they strike with enough force. The foot should have a pointed tip that helps drive it into the soil. Purchase a replacement if the foot is bent or snapped.
Pull out the lock and clevis pin holding the foot in position. Take the foot out of its slot and discard if it is damaged. Place a replacement foot in position with the pointed edge nearest the tiller's tines. Put the lock clip on one side of the foot and slide the clevis through the hole from the opposite side to hold the new foot in place.
Remove the foot as outlined in the previous step and notice the three holes near the top. The hole you pass the clevis pin through dictates the depth of the tilling. Select a the highest hole for shallow cuts and vise versa. Reattach the foot by placing the lock clip on one side and pushing the clevis pin into position.
Remove the handlebar bolts, located at the elbow joint between the grips and the tiller, and lower the bars until they are at waist height. Retighten the bolts to hold the handlebars in position. Start the tiller and keep the handlebars at waist height. Lower the handle roughly 6 to 8 degrees to get the best results; an improperly adjusted foot or handlebars may have resulted in poor tilling in the past.