I have no idea what this is or for what application. Photos and more info is always helpful instead of hoping that the reader will be all-knowing.
Search engines to the rescue!
My results indicate it it is for EZGO vehicles, aka Golf Carts. Quite a pricey part so no wonder you want to see about rebuilding it.
What do the Golf Cart forums say about it? It's possible others might have a hack for servicing them.