Heya Moot, I can only offer this, quoted from page 49, Walk Around # 42, Squadron Signal...
"The Starboard engine nacelle of the Jumo 004B-1 engine. The bullet-shaped covering covers the Riedel-Anlasser RBA-S10. The ring pull handle for the Riedel starter located in the center of the covering is missing."
There is a picture associated with the quote that I am unable to scan right now
However, the picture clearly shows the cover placed on top of a housing which is welded inside the nacelle, just forward of the rotating fins within the main engine housing.
IMO, only the turbofan rotates.
ReDhAwK