I think you'd have to replace the BB, which I suspect would be tough as you'd have to basically disassemble the frame. Perhaps worth it for a hand-made Italian from from the 60s, but for a modern mass-produced frame I suspect not. Or perhaps experts know a way? I think your best best is Surly Warranty, or at least (if you want to take another chance with Surly) see if they'd give you a deal on a replacement frame.