That depends on what kind of blur is that. 1) If its motion blur, you are shooting in low light with low shutter speed and without a tripod. Your hands are not steady. 2) If its a lens blur: 2a: You are again shooting in low light and its difficult for auto-focus to distinguish between contrasts. 2b: There is something else going on with your lens focusing motor. (I ripped my auto-focus system out of my lens long ago, made my lens lightweight and more reliable). Note: Though I wouldn't recommend 2b's example. That would cost you your warranty.
Been there done that, in fact mine was loose so I "fevi-quicked" my headphone cable to the jack and when I pulled the headphone cable out, pretty much everything came out with it. So your options: 1) Change the chip-set.(too costly and not worth it) 2) Use USB sound-card, they usually give you far better sound. I am using steel series Siberia USB sound-card gives me 7.1 surround .
Just encountered the same problem on my iPhone 5 which is also out of warranty. The longer I leave it, the longer I get to work on it when its on again. Your post is from October 2014 so I was wondering you must have figured what's wrong by now. Care to share? Any help at this point of time would be appreciated.