Amazing destruction of an aircraft. I have scoured the parts and all of my FW190 books and documents and came up with nothing.
But, on this Website:
http://www.vrbacky.com/Fw190/Motory.html
in the picture of the BMW801D, the rear end of the starter motor appears similar to the first few images from the picasa web. The slotted (bakelite or phenol ) piece is similar. Most other images of the engine with the starter, that section of the starter is covered with a metallic wrap, possibly of stainless. This site was the only one where it was visible.
I found it searching on google images for BWM801D, and it is easier to visualize from there instead of the vrbacky website.
Again, I am only suggesting similarity.
I would say your comparison of ring clamp collectors is a match.
Tony