Sounds like he knocked all the teeth off the gear. The motor will have to pulled and the cases split to see what all it damaged. It's not that bad of a job, but it is time comsuming. There are alot of parts that can fall out if your not careful. I would reconmend that you get a manuel if you do decide to repair it yourself. you can take a look here and it will give you a general ideal of what you looking at.
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