My external USB won't work - MBR problem

So I found the underlying problem with my USB drive and it seems that it isn't reading properly because the MBR, or the sector the MBR is on, is bad.

How do I rectify this? I've tried using repair utilities but they are unable to find the MBR record. The problem is that the MBR record comes and goes. IE. I can access the drive for 1 minute and then it "disappears" for 5 minutes (like all the files disappear or won't open but the root folders remain).

It seems I can use some tools to recreate an MBR but my understanding is this will wipe the drive which I do not want to do. I have 200gb of music on this drive.

My worst, and I mean WORST case scenario is that I slowly dump the files off one album folder at a time (over 100mb and it craps out before the file copy finishes) which will take me days to do. Best case scenario is I figure out a way to either repair or replace the MBR while not affecting the contents of the drive.