Repair a broken odometer by disconnecting the negative cable from the car's battery, removing the speedomoter needle, and pulling the gear pod off the top of the motor casing. Press the replacement gear into position and reassemble the gauge.
After disconnecting the negative cable from the car's battery, use a flat-head screwdriver to pry the speedomoter gauge away from the dash, and remove the gasket. Pull the entire speedometer gauge out of the dash, making sure not to disconnect any electrical wires. Disconnect only the wire from the back of the gauge.
Lay the gauge face down, and remove the screws from the back of its case. Then, turn it face up. Slowly pull the post used to reset the trip odometer from the gauge. Next, remove the speedometer needle by pinching the round base of the needle and turning it clockwise until it stops. Pull up slowly and gently while rocking the needle slightly back and forth.
Using a mini Phillips-head screwdriver, remove the two screws from the face of the gauge. Once done, pull the motor casing for the odometer out from the dial, and pull the gear pod off the top of the motor casing. Using a mini flat-head screwdriver, pry the odometer planetary gear from the gear pod. Finally, press the replacement gear into position, and reassemble the gauge by reversing the process.