Did not find this in a search, so posting in case others have the problem. Recently noticed my D300 when used with the 70-200 would frequently give a low battery error which resolves with turning the camera off and on again. Enough to be very frustrating. The rotational play in the mount is same as always. Changing battery didn't matter. No issues with other lenses. Found in another forum that people tried DeOxit on the lens contacts - available at Radio Shack for about $14. Others sent to Nikon for evaluation etc. Anyway, I tried DeOxit since I was on vacation. Sprayed it on a relatively clean sock in a car and wiped the contacts. Has worked fine since.