Epson GS6000 superflous lines printing along edges

I recently acquired a four-year-old GS6000 from colleague. The first few prints came out fine. Then it began to print a narrow black line along each edge of the film roll. They appear to be at the extreme margin of the printable area. The lines begin and end with the beginning and end of the image.

Anyone else had this experience; and what did you do to eliminate it?