Getting preview from partial downloads

Hi

I'm downloading a huge file until 50% and no one is sharing it anymore. So i want to get this partial d/l into a single file (or at least the part started from beginning of the file).
So this is my question: Is there any tool out there to do this? Or even simpler: How are the parts organized? Where to strip off this error-checking stuff? The info in 'resumeinfo.txt' i understand, but there is a part (226) which isn't in my temp folder, only '203' and next is '3'.
Can somebody help me with this?

[The Seeker]

for the feature request see this thread for my response.

as to how the parts are organized... JOB-Segment#-1.xlx is always the first segment of Job '#' it is also usually the only file that can be 'previewed'.

Copy this file and rename the extension to what it should be, then do a search for a utility that can fix truncated files of that type.