Once the hole is off-center, it's nearly impossible to correct the mistake. I'd suggest getting a Dremel tool and some diamond-coated bits, and try to get the hole centered back up. Proceed VERY carefully, and when the hole is close to the minor diameter of the threads, use a tap to chase the remains of the bolt out. If you try to force a bigger drill bit through, it will wipe out the threads, and you'll need to either tap the hole for a bigger size bolt or install a heli-coil. Use a very small abrasive bit at high speed, and a light touch, and you might be able to center the hole up without doing any more damage. Good luck!
Jerry
