You'll be better off just junking the lens. The one I had would work if I removed and smacked it too... I did that for a month or so but eventually it just stopped working, fortunately when it did go completely feet up I had another lens with me otherwise I would have been really upset. So do yourself a favor and take it to the shooting range and blast it into photography heaven.Yup. More stuff inside to go wrong. AF, IS, electronic apertures and manual focus by wire, yada yada yada...
Go figure, I got the lens home, put it on a different body - same thing. Next I whacked it 2-3 times on the side as it was powering up and that freed up whatever was stuck. Good as new. Ironically, I did that while I was down there, but it didn't help. Must've been the angle or force or maybe the "third time's the charm."