The rubber ring on my 24-70 f.28 lens started to wear out. It expanded, lost its grip on the lens barrel and came loose. I contacted Nikon support and they told me that this is normal wear. It is actually not a surprise, my 24-70 is the workhorse of my lens collection. No other lens is used more, therefore it is understandable that after 2.5 years of owning it the rubber ring wore out. The spare part cost 19,64 Euros (proud price for a piece of rubber, but that’s what spare parts cost…), installation was very easy, see the video. Also you can see images of the worn out rubber ring and the new one.