You did good June bug, you got 17 years out of a 10 year max,
throwaway lawnmower.
Those things are not the old cub/John Deeres of the good ol'days, that
are still running and fixable.
A 700R4 or turbo 350 they ain't.
Now you know what they look like inside.
Parts it out or find another maybe needing an engine if you are bent on keeping it going.