<p>Figured it out and thought this contribution might still help others coming across this issue.</p>
<p>My girlfriend owns a D70S with the Nikkor 18-70mm and the zoom was getting stuck at the familiar positions. Opened it up in the suggested way by removing the rubber ring, and unscrewing the single locker screw. Surely, one of the screws on the inside had come almost completely loose and I even found a small piece of broken plastic inside (no idea where it came from though).</p>
<p>Upon reassembly I also got the common 'will not focus' issue. After a bit of tinkering I found out that the problem is that the lens can be reassembled in several ways, of which only 1 is correct:</p>
<p>On the inner zoom-ring, there is a special cut-out intended for the single locker screw. If this inner-zoom ring (the outer zoom-ring would be the one that has the rubber band around it) isn't oriented correctly, you can still tighten the screw, but when fully zooming out the inner-zoom ring will block against the screw. This prevents completely zooming out as well, leaving a small gap at the end of the lens. Only if the cut-out is aligned so that the locking screw fits between it will you be able to zoom fill out and will the AF function.</p>
<p>Now the trick is to position the inner zoom-ring before reassembly so that the cut-out aligns with the metal bit that has the thread for the locking screw. Perhaps put a little mark on the inner zoom-ring and the lens body to see if they still align when continuing. After that, it's a matter of sliding the outer zoom-ring (it also has a screw hole) on the lens body, and let gravity + a bit of shaking do the work to make the inner-ring's grooves catch the diamond shaped bits of plastic on the front lens body.</p>
<p>Lens now works like a charm!</p>
<p>I can supply some pictures if needed, or just mail/reply if you have question.</p>
