Here's a better look at the piece in question, on an original grenade:
But IMO there is no evidence that that piece was inside the emitter in the Chronicles pic, and screen caps show that it was definitely NOT in the emitter during certain parts of production.
There was once a theory put forward about some blobs matching hole positions, but in fact they don't match the right hole positions if you test it out photographically, and other features contradict the idea as well. If I can dig up my relevant pics I will post one.
Anyway, this piece is super easy to make, any amateur with a lathe can do one for you, or if you're clever with a drill press and have a pretty sturdy one you can make one yourself.
Ah, here's one. The red line points out that the grey 'blob' (sometimes taken to be 'solder' such as sometimes appears on the 'barrel clip base') actually continues way beyond the place where the clip base would be, and could easily be an angled streak on the inside of a hollow cylinder.
Here's an analysis of this issue I did before we had screen caps from the DVDs. Elipses (circles in perspective)
with their centers marked are used to show approximate positions along the length of the saber of various features. Despite the rough nature of the analysis, the 'hole' feature inside the emitter is clearly deep in the emitter:
Documentary footage shows Alec Guinness holding the prop right before a prop man switches it for a bladed stunt for this scene where he turns on the saber, so this is the hero prop.