they have a rubber insert for vibration and they deteroiate and the outer part comes apart from the inner...get a flashlight or turn the wheel to the right and you should be able to pull the flap away enough to see the crank...get someone to start it and see if the inner part is spinning and the outer part is not...if the inner part is not speinning either then its either sheared the crank key or has broke the snout off the crank....hopefully just sheared the key