I’m not a data recovery professional, but if the HDD has an internal problem, then there’s not much that you can do. 
I was hoping that HD Sentinel or HDDScan would be able to see the HDD’s model number, eg WD320xxxx, but it appears that the drive is not reporting this information.
Here are two examples of good drives:
http://hardverapro.hu/apro/wd_my_passport_kulso_2_5_250gb/hsz_2-2.html (250GB My Passport)
http://www.emag.ro/hdd-extern-western-digital-elements-1-5tb-3-5-5400rpm-usb-2-0-negru-wdbaau0015hbk/pd/EBJP7BBBM/ (1.5TB My Book Elements)
The following example is of a bad drive with a firmware problem. The HDD is communicating with the bridge IC, but it is reporting a “factory alias” rather than its correct model number. It is also reporting an incorrect capacity.
http://puhpol.0pk.ru/viewtopic.php?id=171
Here are apparently good examples for other models and manufacturers:
http://www.intercon.hu/vatera/samsung_g3.txt
http://ebay.stephenemert.com/ebay/F30E20AC.txt
http://ebay.stephenemert.com/ebay/YFDYFHD6452.txt
http://ebay.stephenemert.com/ebay/E124W67E.txt
http://forums.seagate.com/stx/board/crawl_message?board.id=ata_drives&message.id=26098
http://www.techsupportforum.com/forums/f16/hard-drive-failure-637224.html
http://lime-technology.com/forum/index.php?action=dlattach;topic=18965.0;attach=10250
http://www.pcreview.co.uk/forums/so-one-usb-port-not-equal-other-usb-port-t3978656.html
http://homenet.beeline.ru/index.php?showtopic=265386
http://hardwarebg.com/forum/archive/index.php/t-200639.html
http://skodamea.ro/forum/viewtopic.php?f=69&t=421&p=6676
http://spb-device.livejournal.com/12016802.html
