I made another version of this image where I just cropped down to the area you are talking about. But, even this small crop is still over 8MB, which I can upload to Photobucket, but the IMG link may reduce it. As you can see the thread detail is there.
Also, likely because of the scanner restrictions and transparency's curl. NARA doesn't allow any holder to hold or keep the transparency flat. The scanners NARA provides for researchers to use are Epson 9000 large format flatbed scanners. You put transparencies on the plate and lower the lid on it. There is a gap between the top and the plate, if the transparency isn't flat parts of the transparency isn't in focus. Most (or All) flatbed scanners have a very narrow focal plane where the image is in perfect focus at the plate surface.
The transparencies at NARA are kept in cold storage. When a researcher "pulls" a transparency, it is left at room temp before it can be handled and scanned. Some transparencies will have a bad curl in just one dimension, like just off a roller. Others can have a curl from the center out to all edges. Lowering the cover to the plate will take out most of the curl. But, there will be areas on the transparency that will be out of focus ... normally at the edges, like in the foreground of this image. If you can, and not get yelled at, using something flat like cardboard placed on the edges of the transparency will help get the transparency flat. For most subjects the photographer has the subject in the center of the transparency/negative, so this isn't a problem for a good scan. This can be a problem scanning slides (like 35-mm slides) with a flatbed scanner because the slide frame holds the transparency above the flat plate, making for non-ideal scanning. Unless you have some software to correct the image output or have a designed for the purpose slide scanner, you are left with out of focus images.
When Chuck Haberlein at NHC had color prints made from the transparencies (a two step process, first inter-negative, then a print from the negative) they were made the old fashion way with film and enlarger to paper. AKA, the focal plane ca be controlled and the transparency is held flat with a holder. Chuck just had a flat print to scan.
Another interesting issue I saw with some color transparencies, particularly the large format (8x10 and larger transparencies/negatives) were due to the optics of the camera used. Without getting too much into optical theory and making of camera lens, some cameras used for color film were not designed to do so. Unless designed to correct it, the lens will spread out the spectrum so that the individual colors don't align in the image, making it look blurry the further you go out from the center. The image that passes through a lens is circular. When designing a camera lens, because you are dealing with square/rectangular film, the circular image that the lens "see" is kept larger than the size of the transparency/negative so that the "sweet spot" of the optics is used. On some images I saw that the camera wasn't using a sweet spot, they were filling the whole transparency with the whole lens image. This creates a circular "shadow" on the film where the center is in focus, but as you go out from the center, the image gets blurrier and blurrier. You can see that there is a darker area in the corners of the full image.