John Deere garden tractors use an electric starter that resembles the starter you would see on a car. In fact, they work in the same manner. When you turn the ignition key, the starter solenoid, which mounts to the starter, forces a small gear inside the starter motor to turn. The gear then turns a gear inside the engine and the engine comes to life. At times, the brushes inside the starter motor fail. When this happens, you can replace the starter with a new one.
Raise the hood on your John Deere garden tractor. The battery and starter both mount under the hood.
Disconnect the negative (black) battery cable form the battery terminal. Push the red cover off the positive (red) battery cable and then remove the cable from the battery terminal. Use a wrench for this.
Locate the starter motor on the bottom side of the engine block. John Deere has used many different engines over the years. Therefore, use the replacement starter as a visual reference for locating the exact place on the engine where the starter mounts. It will mount towards the bottom of the engine.
Disconnect the wire terminals that secure the ground wire and the positive wire to the backside of the starter with a wrench.
Disconnect the wiring harness that connects to starter to the electrical system. The harness is a "plug in" type where you push in on a locking tab and then pull on the harness to disconnect it.
Remove the bolts that secure the starter to the engine block with a wrench and then pull the starter away from the block. In some cases, you will see a set of shims mounted between the starter and the engine block. Keep the shims and transfer them to the new starter.
Place the new starter against the block. The base of the starter must rest flush against the block to ensure the gear inside the starter motor seats with the gear inside the engine. Secure the starter to the block with the original bolts.
Reattach the ground and the positive wires to the backside of the starter and then plug the wire harness back in.
Reconnect the positive battery cable and then the negative battery cable.