The medium box is a lot more expensive because you can make it weigh a lot more. I sent one to a friend in the UK several months ago and it weighed 22 lbs.
I wouldn't expect neodymium magnets to lose permeability but I haven't researched the topic. I would think it more likely that the problem is whatever holds the head assembly in the park position has become a bit too sticky. Either lubrication has gummed up or a rubber pad has turned to goo. If the magnets were weak I would expect seek problems since the response would be much slower than the servo loop is expecting.
While I would only do it as a last ditch effort, once in a while you *can* get away with opening up a hard drive, just don't run it with the cover off if you can avoid it. I fixed a 40MB MFM drive around 20 years ago which required removing the cover, and afterward it ran fine until I got rid of the PC it was in ~5 years later.
I wouldn't expect neodymium magnets to lose permeability but I haven't researched the topic. I would think it more likely that the problem is whatever holds the head assembly in the park position has become a bit too sticky. Either lubrication has gummed up or a rubber pad has turned to goo. If the magnets were weak I would expect seek problems since the response would be much slower than the servo loop is expecting.
While I would only do it as a last ditch effort, once in a while you *can* get away with opening up a hard drive, just don't run it with the cover off if you can avoid it. I fixed a 40MB MFM drive around 20 years ago which required removing the cover, and afterward it ran fine until I got rid of the PC it was in ~5 years later.