Starter Spins But Flywheel Does Not on John Deere Mower?

I have a John Deere Sabre riding lawn mower with a Briggs/Stratton motor. I have never have had any problems with it until now. The starter gear spins, but the fly wheel doesn't. Does this mean the starter gear is worn out or could it be a more major problem? The mower is 14 years old.

By Shirley Luetge from TX