Maybe a trip to the service center is not needed. Can you post images that show the defect? I hope you are not viewing images at 100% shooting at 1/15th with a 24mpx camera, even the best technique that worked with film just fine will not be fast enough for a high resolution digital camera due to the difference in viewing scale. Is anything in the frame sharp when the center isn't? Is this occurring in all focus modes, even LV? Using tripod, try posting a scene with VF mode and one of the same subject in LV.