My starter motor wasn't engaging with the flywheel properly.
So I decided to pull it apart.
First take out the long screws:
Yep, it's a little dirty:
Then after you've taken off the solenoid, you can take it apart:

At step two, a little ball bearing fell out. You can see it in the third pic. Can anyone tell me where it came from?
And what grease should I be using when I put it back together? I've got bearing grease and molly grease here.