Hey there, @Robertwhyte!
I'd strongly recommend you consider contacting a professional data recovery company for assistance. Using third-party tools by yourself is potentially dangerous, especially if you are not aware of the exact type of corruption/damage on the hard drive itself. I'd advise you to check its SMART attributes & health by running a Diagnostic HDD utility
first. If you are dealing with too many bad sectors, it's possible that the files you have retrieved are incomplete or corruped as well.
If the data is very important, a professional data recovery company is your best bet on getting any of the files back.