For whatever it's worth.. More and more floppies are really ratbaggy these days. I just had a box that was totally not reading. It would read the first 4 or 5 tracks then start giving errors. I cleaned the drive head with a floppy cleaner, and it proceed to go a little further. I'd repeat the process 5 or more times to grab a whole disk! This was untenable.
I took a damp Q-tip and brushed it vertically up and down the cutout slot where the head reads. Rotated the disk a bit and did it again. And again. After about 2 minutes the disk was swabbed. And it read flawlessly on the first attempt.
It appears some of the oxide's lubricant dried on the surface over time. And it came off when reading the disk in the drive - thus clogging the head. Pre-buffing with the Q-tip seems to have prevented the clogging. And the Q-tip wasn't picking up much oxide, it was barely tanned. I used about 5 AA Batteries' weight worth of pressure. And you work on a flat paper surface, 20 sheets is fine.
It wouldn't be hard to build a machine to pre-buff the disk automatically. Though it must be noted a vertical motion worked and not a linear rotational motion. So running it in the drive with a big-ass pressure pad won't fix the problem.
Don't know the longevity of a disk after such treatment. But they do last long enough to read them at least several days later. That may be irrelevant because once you got the data off, it's throw-away material.