I have a mower to fix from my mother in-law. I order a new starter motor and it will not turn the engine over. Also I notice broken teeth on the engine fly wheel. One section of teeth for about 6 inches is totally gone. The starter engages but will not turn the fly wheel. The old starter has a broken shaft in it. The mower did run okay. I have replaced the battery, plugs, air and gas filters, and changed oil. The motor is not seized. Any suggestions????