Are there any possible causes for a starter to spin but not engage the flywheel, other than bad solenoid, missing teeth on flywheel, or low battery? This problem first occurred with a 2 year old starter. After installing a new starter the problem still exists.
WITH THE STARTER REMOVED IS THERE FLEX OR MOVEMENT IN THE FLYWHEEL?
I GUESS A BETTER TEST WOULD BE TURN THE ENGINE OVER AT THE HARMONIC BALANCER WITH A WRENCH OR RATCHET, AND WITH THE STARTER REMOVED, USING A "DIAL INDICATOR" OR A STATIONARY "INDICATOR"---SEE IF THE FLYWHEEL RUNS TRUE OR IS THERE A "WAVE" IN IT.
I HAVE SEEN FLYWHEELS ON AUTOMATICS CRACK NEAR THE BOLTS THAT HOLD IT TO THE CRANK, AND THE FLYWHEEL SORTA FLEXES AT THAT POINT, THE TEETH GET FURTHER FROM THE STARTER TEETH