As others have said, looks like a good head clean will fix this, old floppies even when stored well still get
a thin layer of "gunk" build up over the surface and this gets transferred to the head.
When I did my old disks some years ago, I kept the drive open and had to clean the every few disks, hopefully
that's all that's wrong with yours.
Also check the surface of the disk, another thing that can happen is the magnetic material degrades over the
years, I've had a few disks where the material has scraped off, you can see rings on the disk surface, if it's
done this, it's highly likely the disk is toast.