What to s=check when your aveo wont crank

i had replaced my starter 4 months ago or so and yesterday it wouldn't start, i could hear the Bendix gear kicking forwards, so i knew it wasn't the solenoid this time so i got the car on blocks and found this:
Attachment 6053
I guess in the last few months the nut worked its way out and off..... at least i was able to push start it at work the other day.

Ha!

Looks like a bit of arcing went on there as well judging by the ash.burnt look on part of the threads.

Push starting can be fun too though. Been there, done that. (Neighbours always stare.)

Yeah, the hole in the contact was round, now its oval.....
At least my aveo fires on the first crank, makes it real easy to push.