I've got a "long-nose" 50mm Nikkor as described here: http://www.destoutz.ch/lens_50mm_f1.8_3209712.html Was looking for it for quite a bit (and eventually spend 70€), as read somewhere it is one of the sharpest fifties wide open. After shooting with it for a couple of days (to my amateur eyes the results are very good), I noticed that the most front part of the barrel/ring that comes out when focusing is a bit loose. Then I noticed a screw on the side of that ring that was also loose. I loosened it further with a small flathead, which also released the ring. I took the ring off just to see what's inside - and found there three screws, all sealed. Without doing anything stupid, I screwed the ring back in and tightened it (not with extra force, but quite tight I think), and then fixed it with the screw on the side. That solved the problem of the loose ring, but got me curious and lead to the "How to evaluate used lenses" thread on this forum. I went through the list and when shaking the lens I heard a rattling noise. After some experiments I found out that its the front element making it: if I hold the front and rear elements of the lens with my fingers (with a microfiber cloth) and shake it - the rattle/clicking goes away. Then I checked and I can actually rotate the front element, e.g., when I would clean it with a microfiber cloth. Should I return the lens? Is it the ring that is not tight enough, and can I fix it by simply tightening it? Or the screws inside? As I mentioned earlier, the IQ seems fine and I can focus to both close and far ranges, even past infinity with the cheap adapter that I use.