Why do good floppy disks go bad?

[Jules Richardson]

On 04/07/2016 12:11 PM, Chuck Guzis wrote:
> My water heater supposedly has a guarantee for replacement for as long
> as I own my home.  I haven't had to claim a replacement yet.

I wonder if that also covers parts - e.g. elements and thermostats - or if 
they try and weasel out of it and only allow a claim when something which 
really does require outright replacement happens?