Exmark 60 inch with kohler 27hp engine, need help starter wont engage

Hi everyone, my starter on a Kohler Command 27hp Engine, won稚 engage, I used a Heavy-duty car battery charger and jump start at the starter solenoid, I can hear the starter engaging but it is just free spinning; it is not engaging with the fly wheel....any idea what could be wrong. I just bought this mower today and the guy told me that the repair shop told them the engine was gone, the previous owner of the mower told me the one day he went to start the engine and he heard a loud noise and starter start spinning freely, he bought another mower and sold this one to me.. Any idea what could be wrong? Is it possible that the tooth on the fly wheel has broken off?

I will really appreciate your help.

Thank You