> But I have to actually put quite a bit of force on the back of the
> cable on the problematic hard drive in order for it to spin up properly

Even though it seems as though the drive is at fault, it still may be just the cable - the nature of the fault with the crimp on the middle connector means that even the slightest movement (even heat expansion) can cause the connection to fail. Something as simple as a slightly offset pin on the drive could cause a problem.

email support and ask for a replacement cable first - it's free of charge and is worth doing anyway.

Also, IBM consider these drives OEM units and will not issue an RMA to end users.