I have owned my 28-70 for several years now and it is by far my most used lens. A few years ago it was experiencing a condition where the focusing would continuously "hunt" and never end up in focus. I took it to a Nikon Authorized Center who originally diagnosed it with needing a new motor and ended up replacing the zoom guides and did a check and clean. It's been fine ever since. Recently the lens has started a squeaking sound when focusing. At first it was intermittent and now its pretty much constant. The lens works fine though. Everything I'm reading seems to indicate a new motor is needed. I have come across a couple of articles that have said the problem might be mechanical rather than electrical. They said to switch to manual focus and see if the squeaking continues. It did. I worked the lens a few times manually focusing from one end of the range to the other. The squeaking has now ceased when using auto focus. At this point I'm not sure what to think. Has anyone else tried this method and did it work?