I'm betting the outer emitter moves in and out as follows - In the cut away of the nozzle there are 4 arcs above and below the emitter. I believe these arcs to be the profile of coarse threads. I bet there is a plastic nub which protrudes off the emitter into these threads. When the nozzle it turned the nub moves forward and back in the threads moving the connected emitter in and out. If this is true then for those with an emitter which no longer moves in and out, I'm betting this nub has been broken off.
In the illustration if the nub(s) are oriented vertically then they won't show up in the cut away, If oriented horizontally the same is true. If horizontal, you have to imaging a nub protruding back into the illustration. A front facing horizontal nub would also not be visible.
Greg