My 24-120mm AF Nikkor Zoom has an inconsistent problem on both of my F5s and my D200. When I mount it on any of the cameras it sometimes says FEE on the LCD. That means that it is not properly set at the minimum aperture. But it is. The aperture ring feels normal and does not in any way feel loose, and I have wiped off the contacts in the lens mount area down. So I think they are clean. It usually is fine when first mounted on the camera bodies but then the dreaded FEE appears. My other AF Zooms all work fine, but this is the lens I use most, so I guess it has the most use by a country mile. Is there a solvent, such as alchohol or whatever I could wipe in the contact bumps to maybe clean them better, or is there something else I should try or look for. Thanks, Don