Yes, welding on a blob and shaping with a file is a good solution. It can be done with minimal heat, so the paint damage is limited to the tab.
If the OP doesn't know a welder, he can do a cold repair by drilling a small hole and pressing a pin, maybe a piece cut from a spoke. Then build around that with metal/epoxy fill, and filing to final shape. If using this method the pin should be as near to the ultimate face ad possible, so the B-screw rests on it, and the fill braces it from the back.
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