Hard Disk GPT Header Corrupted I have replaced my Mac's original hard drive and now trying to use it as an external hard disk with an enclosure. However I have ran in to the below issue and I cannot access any data on this disk anymore.

Axiom:~ migara$ sudo gpt show -l /dev/disk3
    start        size  index  contents
        0           1         PMBR
        1  1465149167 

Axiom:~ migara$ sudo gdisk /dev/disk3
GPT fdisk (gdisk) version 1.0.1

Caution: invalid backup GPT header, but valid main header;
regenerating backup header from main header.

Caution! After loading partitions, the CRC doesn't check out! Warning!
Main and backup partition tables differ! Use the 'c' and 'e' options
on the recovery &amp; transformation menu to examine the two tables.

Warning! One or more CRCs don't match. You should repair the disk!

Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: damaged

**************************************************************************** 
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT,
but disk verification and recovery are STRONGLY recommended.
****************************************************************************

Command (? for help): p
Disk /dev/disk3: 1465149168 sectors, 698.6 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): BD148DB7-177A-4219-9CA1-F7C2884DB38B
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 1465149134
Partitions will be aligned on 8-sector boundaries
Total free space is 262157 sectors (128.0 MiB)

Number  Start (sector)    End (sector)  Size       Code  Name
   1              40          409639   200.0 MiB   EF00  EFI System Partition
   2          409640       732144615   348.9 GiB   AF00  Customer
   3       732144616       733414151   619.9 MiB   AB00  Recovery HD
   4       733414152      1464886983   348.8 GiB   AF00  Macintosh HD 2 
  25       183143645               6   16.0 EiB    FFFF  TEST
  57           51205        91518076   43.6 GiB    AF00
  58        91518077        91676768   77.5 MiB    AF00  

Command (? for help): q
Axiom:~ migara$ diskutil list /dev/disk3
/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *750.2 GB   disk3
   1:                       0xEE                         93.8 GB    disk3s1


Could someone please help me? (@klanomath)
Thanks a lot for taking a look at it. I managed to repair this by creating partitions again.

I could find the GUIDs for each partition with gdisk 

Axiom:~ migara$ sudo gdisk /dev/disk3
GPT fdisk (gdisk) version 1.0.1

Caution: invalid backup GPT header, but valid main header; regenerating
backup header from main header.

Caution! After loading partitions, the CRC doesn't check out!
Warning! Main and backup partition tables differ! Use the 'c' and 'e' options
on the recovery &amp; transformation menu to examine the two tables.

Warning! One or more CRCs don't match. You should repair the disk!

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: damaged

****************************************************************************
Caution: Found protective or hybrid MBR and corrupt GPT. Using GPT, but disk
verification and recovery are STRONGLY recommended.
****************************************************************************

Command (? for help): i
Partition number (1-58): 1
Partition GUID code: C12A7328-F81F-11D2-BA4B-00A0C93EC93B (EFI System)
Partition unique GUID: 809BE30A-C34D-46BF-9135-545BCA0367F4
First sector: 40 (at 20.0 KiB)
Last sector: 409639 (at 200.0 MiB)
Partition size: 409600 sectors (200.0 MiB)
Attribute flags: 0000000000000000
Partition name: 'EFI System Partition'


Then create partitions with gpt.

Axiom:~ migara$ sudo gpt add -b 40 -i 1 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk3
disk3s1 added
Axiom:~ migara$ sudo gpt add -b 409640 -i 1 -s 731734976 -t 48465300-0000-11AA-AA11-00306543ECAC disk3
gpt add: disk3: error: entry at index 1 is not free
Axiom:~ migara$ sudo gpt add -b 409640 -i 2 -s 731734976 -t 48465300-0000-11AA-AA11-00306543ECAC disk3
disk3s2 added
Axiom:~ migara$ diskutil unmountDisk disk3
Unmount of all volumes on disk3 was successful
Axiom:~ migara$ sudo gpt add -b 732144616 -i 3 -s 1269536 -t 426F6F74-0000-11AA-AA11-00306543ECAC disk3
disk3s3 added
Axiom:~ migara$ diskutil unmountDisk disk3
Unmount of all volumes on disk3 was successful
Axiom:~ migara$ sudo gpt add -b 733414152 -i 4 -s 731472832 -t 48465300-0000-11AA-AA11-00306543ECAC disk3
disk3s4 added
Axiom:~ migara$ diskutil unmountDisk disk3
Unmount of all volumes on disk3 was successful


Thanks again!