Hello, I know about spinrite, but I didn't think that worked on usb-attached external drives. I've got a terabyte external drive connected by usb, it's an enclosure, but not removable, i.e. the drive came in it and it's sealed not meant to be replaced. This enclosure took a spill and hit a carpeted ground apartment say maybe four feet and it didn't show up for a while. I recycled it, disconnected and reconnected everything, and it shows up but it took what looks like casing damage and I'm hoping it didn't take internal damage, it's not making any noises and it is showing up again, I'd like to know what others use to test their external drives? Also on the subject, is anyone using the network-attached terabyte or greater drive? Which one can be recommended? Thanks. Dave.