I've replaced the failed 2TB HDD in my TC with a 4TB HDD (both WD Green drives). I've used the Airport Utility to try and set it up but keep getting the error "internal disk needs repair". I've tried soft, hard and factory default resets, but neither Finder or Disk Utility 'sees' the TC. If I use Airport Utility/Manual Setup/Disks, I can see the disk (although it only 'sees' 3.6TB) and it's S.M.A.R.T. status is 'Verified'.

I've returned the 4TB HDD and got a new one and installed it, but still get the same error. Anyone have any ideas what the problem might be? The OS on my iMac is 10.6.8, but I'm under the impression this isn't relevant to the TC set up.