RPF PREMIUM MEMBER
I have a theory about the nipple on the V3 in the b/w still from ROtJ (Vader holding saber on Endor before his dialogue with Luke). I think the nipple was used to hold the prop together. And I habe a gut feeling the nipple on the V2 serves the same purpose.
The most befuddling thing is that doesn't have a nipple in that pic.
So unless the V3 was altered to be more like what we know today, then---with a grub screw in the emitter---to hold it all together sans a nipple, and that detail has just remained camera shy for the better part of 20 years; I honestly have no clue as to how this thing held together knowing about its construction now.
Unless there's tape on it in this and we can't make it out, or it's glued together, if it isn't mechanically held together with screws, the emitter would just fall off.