Looks like it's not conceived to be serviceable, and I can't find information about it on the web.
If the actual drive can be removed from the casing, my bet would be to remove it and mount it into another casing. You can get some empty casing in many computer related stores. Just make sure that the new casing support IDE drives as your 250 Gb drive is several years old and likely to be of the IDE variety, not a SATA.
If your computer is a desktop, you can also probably install it inside the computer itself as an additional drive.