I had a customer bring a wheel in with all the sprocket bolts broken. They were going to try to drill them out which most likely would have resulted in a ruined wheel. Instead I tig welded the bolts up past the surface of the hub, dropped a nut on there and welded them up.
I welded all five and then sprayed penetrating lube on them. Next fire up your torch and heat the hub until your lube is boiling and bubbling!