Before I swiped I looked inside. I don’t have a sensor loop or anything like it. But as I looked inside angling the camera with the bright light source I could see reflections where the spots would be that are indicative of light reflecting of a shiny surface which was different than the surrounding sensor area. And as Charles (N4TVC) stated, it appears some of the spots smeared, so it would appear that the spots are definitely not solid/dust but some type of fluid/paste.
So Stan, do you have any information or comment about the location of the Mirror Drive Motor Unit that was suggested in that DPreview post?