After inspecting the negatives by eye I realized that I couldn't see anything that would account for the marks. The previous scans I posted here were done with a Nikon Coolsan V. I also have an Epson V700 and decided to try scanning them again and what do you know...



The marks are not there and I think the dark area at the top of the right side images is from the lousy film holder not holding the film flat. That image is at the end of a strip so I think it's curving in slightly.