In my early days of tying, I had that happen to several bobbins. IMO, unless you're a machinist or in some other profession where you have free access to the required tools, and can make those repairs, it would likely cost more than the new bobbin to try to repair the old one, particularly if you need someone else to do it.
I now only buy the ceramic type, specifically those made by Griffin, and have never had a problem with them. I've got about a dozen of them now of various types.
Spend the money & get the better bobbin, it will be worth it in the long run if you do a lot of tying.