I have a john Deer L100 and the fly wheel keeps sticking when I try to crank it. It has now broken the starter what do I need to do to fix the fly wheel before replacing the starter?

Hi,
If it is one with a plastic ring gear, then replace it with an aluminum one available in kit form. Usually the plastic ones will be damaged if you "hit" the starter with the engine running. Often you can visually identfy the damaged area.
Peace,
Clarke