Oil pump primary drive gear keeps snapping pictures included HELP

I own a 2005 yz450F. While riding the other day it locked up the back tire and just died out of the blue. I tore into it and found that the oil pump primary gear had snapped in half came off and was all tangled up in everything. Upon falling off it left alot of metal flakings and cut into the case some. The preious owner said that the same thing had happened in the past and he had fixed it once already. Dont know why the gear would do it again and need help finding out why. I dont know if it was an installation mistake or what. If someone could help that would be great. Also can I just file down the metal shavings where it cut into the case and be okay as long as nothing can touch it? I will add the pictures in one minute.

The oil pump gear is driven by the pump idler gear, which is driven by the kick starter gear on the back of the primary driven gear assembly (clutch basket). If this is a repeat failure, it's probable that the idler gear is damaged, having a malformed tooth that's breaking pump gears. There are a total of 5 gears in that train that mesh together, and they should all be checked.

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