Hard drives almost always contain some potentially compromising information, such as credit card and social security numbers. You should always wipe a hard drive before turning it over to someone else. But that job is particularly difficult if the hard drive no longer works.
But why would you even need to secure a drive that doesn't work? If the drive's electronics are fried but the mechanical components are still working, someone could fix it without destroying your data, which could then fall into the wrong hands.
What you have to do is find someone who can degauss your drive. Translation: Someone who can erase it with a very powerful, very expensive magnet.
One thing you could do is talk to the people you're returning the drive to, whether that's the manufacturer (Dwma's drive died while under warranty) or a recycling center. They may offer a policy of degaussing drives when they receive them.
If they don't, or if you don't trust them, you can find a company in your area that degausses drives.
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