Thanks so much for your wonderful TestDisk. Have used to repair failed Raid0 in the past. This time a non-bootable, 1 Partition (not counting the Microsoft reserved 128MB), storage-only Seagate 3TB kept disappearing. I had run chkdsk before to repair damaged sectors and had moved all but 200GB to other backup. I started chkdsk again but it crashed repeatedly so tried TestDisk which reported bad GPT header and incorrect  sector size. Ran Analyze which shocked me by jumping to 99% in half a second (Kudos on the speed-up) but pressing STOP did nothing. Third attempt on Quick Search I managed to hit STOP quickly enough to see Deeper Search option appear. 
Don't know why my drives only show as Physical Drives and never in Disk /dev/sda as per your manuals?
Anywho, the drive in question is Disk \\.\PhysicalDrive4 . It should be identical in geometry to Disk \\.\PhysicalDrive7 as both same Seagate 3TB with one partition. But PhysicalDrive4 has Blocksize=512 whereas it should be Blocksize=4096 as in PhysicalDrive7. 
However I am afraid to simply change the geometry until I backup the last remaining files which I am currently copying after successfully listing the files at the bottom of the TestDisk log, but it is taking forever. 
Can I stop the slow copying and simply change the geometry to match that of the identical PhysicalDrive7 (CHS 45600 255 63, sector size=4096) and then somehow correct this quicker? If not, what steps should I take to actually write the found correct NTFS partition to the disk?
Here is the testdisk.log:
Sat Aug 01 23:33:20 2015
Command line: TestDisk
TestDisk 7.0, Data Recovery Utility, April 2015
Christophe GRENIER <grenier@cgsecurity.org>
http://www.cgsecurity.org
OS: Windows 7 (7601) SP1
Compiler: GCC 4.9, MinGW 3.11
Compilation date: Apr 18 2015 13:02:07
ext2fs lib: none, ntfs lib: 10:0:0, reiserfs lib: none, ewf lib: 20120504, curses lib: pdcurses build  3401
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive0)=240057409536
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive1)=240057409536
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive2)=2000398934016
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive3)=2000398934016
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive4)=3000592982016
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive5)=200049647616
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive6)=1000204886016
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\PhysicalDrive7)=3000592977920
filewin32_getfilesize(\\.\PhysicalDrive8) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\PhysicalDrive8) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\PhysicalDrive8
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\C:)=239949840384
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\D:)=240051487744
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\E:)=2000263577600
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\F:)=2000263577600
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\G:)=3000457232384
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\H:)=79949689344
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\I:)=3000584577024
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\J:)=120097313280
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\K:)=0
Warning: can't get size for \\.\K:
filewin32_getfilesize(\\.\L:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\L:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\L:
filewin32_getfilesize(\\.\M:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\M:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\M:
disk_get_size_win32 IOCTL_DISK_GET_LENGTH_INFO(\\.\N:)=1000202241024
filewin32_getfilesize(\\.\O:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\O:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\O:
filewin32_getfilesize(\\.\P:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\P:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\P:
filewin32_getfilesize(\\.\Q:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\Q:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\Q:
filewin32_getfilesize(\\.\R:) GetFileSize err Incorrect function.
filewin32_setfilepointer(\\.\R:) SetFilePointer err Incorrect function.
Warning: can't get size for \\.\R:
Hard disk list
Disk \\.\PhysicalDrive0 - 240 GB / 223 GiB - CHS 29185 255 63, sector size=512
Disk \\.\PhysicalDrive1 - 240 GB / 223 GiB - CHS 29185 255 63, sector size=512
Disk \\.\PhysicalDrive2 - 2000 GB / 1863 GiB - CHS 243201 255 63, sector size=512
Disk \\.\PhysicalDrive3 - 2000 GB / 1863 GiB - CHS 243201 255 63, sector size=512
Disk \\.\PhysicalDrive4 - 3000 GB / 2794 GiB - CHS 364801 255 63, sector size=512
Disk \\.\PhysicalDrive5 - 200 GB / 186 GiB - CHS 24321 255 63, sector size=512
Disk \\.\PhysicalDrive6 - 1000 GB / 931 GiB - CHS 121601 255 63, sector size=512
Disk \\.\PhysicalDrive7 - 3000 GB / 2794 GiB - CHS 45600 255 63, sector size=4096
Drive C: - 239 GB / 223 GiB - CHS 29172 255 63, sector size=512
Drive D: - 240 GB / 223 GiB - CHS 29184 255 63, sector size=512
Drive E: - 2000 GB / 1862 GiB - CHS 243184 255 63, sector size=512
Drive G: - 3000 GB / 2794 GiB - CHS 364784 255 63, sector size=512
Drive H: - 79 GB / 74 GiB - CHS 9719 255 63, sector size=512
Drive I: - 3000 GB / 2794 GiB - CHS 45600 255 63, sector size=4096
Drive J: - 120 GB / 111 GiB - CHS 14601 255 63, sector size=512
Drive N: - 1000 GB / 931 GiB - CHS 121600 255 63, sector size=512
Partition table type (auto): EFI GPT
Disk \\.\PhysicalDrive4 - 3000 GB / 2794 GiB
Partition table type: EFI GPT
Analyse Disk \\.\PhysicalDrive4 - 3000 GB / 2794 GiB - CHS 364801 255 63
hdr_size=92
hdr_lba_self=1
hdr_lba_alt=5860533167 (expected 5860533167)
hdr_lba_start=34
hdr_lba_end=5860533134
hdr_lba_table=5860533168
hdr_entries=128
hdr_entsz=128
hdr_size=92
hdr_lba_self=5860533167
hdr_lba_alt=1 (expected 1)
hdr_lba_start=34
hdr_lba_end=5860533134
hdr_lba_table=5860533135
hdr_entries=128
hdr_entsz=128
check_part_gpt failed for partition
 1 P MS Reserved                   34     262177     262144 [Microsoft reserved partition]
Bad GPT partition, invalid header checksum.
Trying alternate GPT
No FAT, NTFS, ext2, JFS, Reiser, cramfs or XFS marker
 1 P MS Reserved                   34     262177     262144 [Microsoft reserved partition]
 1 P MS Reserved                   34     262177     262144 [Microsoft reserved partition]
 2 P MS Data                   264192 5860532223 5860268032 [Basic data partition]
Current partition structure:
Bad GPT partition, invalid header checksum.
Trying alternate GPT
No FAT, NTFS, ext2, JFS, Reiser, cramfs or XFS marker
 1 P MS Reserved                   34     262177     262144 [Microsoft reserved partition]
 1 P MS Reserved                   34     262177     262144 [Microsoft reserved partition]
 2 P MS Data                   264192 5860532223 5860268032 [Basic data partition]
search_part()
Disk \\.\PhysicalDrive4 - 3000 GB / 2794 GiB - CHS 364801 255 63
NTFS at 16/113/34
filesystem size           5860268032
sectors_per_cluster       8
mft_lcn                   786432
mftmirr_lcn               2
clusters_per_mft_record   -10
clusters_per_index_record 1
NTFS part_offset=135266304, part_size=3000457232384, sector_size=512
NTFS partition cannot be added (part_offset<part_size).
NTFS at 16/113/34
filesystem size           5860268032
sectors_per_cluster       8
mft_lcn                   786432
mftmirr_lcn               2
clusters_per_mft_record   -10
clusters_per_index_record 1
     MS Data                   264192 5860532223 5860268032
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
Search for partition aborted
Results
   P MS Data                   264192 5860532223 5860268032
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
interface_write()
 1 P MS Data                   264192 5860532223 5860268032
$MFT has invalid magic.
ntfs_mft_load(): Failed.
Failed to load $MFT: Input/output error.
Failed to startup volume: Input/output error.
$MFT has invalid magic.
ntfs_mft_load(): Failed.
Failed to load $MFT: Input/output error.
search_part()
Disk \\.\PhysicalDrive4 - 3000 GB / 2794 GiB - CHS 364801 255 63
NTFS at 1/5/5
Warning: number of bytes per sector mismatches 4096 (NTFS) != 512 (HD)
filesystem size           732563456
sectors_per_cluster       1
mft_lcn                   786432
mftmirr_lcn               366281727
clusters_per_mft_record   1
clusters_per_index_record 1
NTFS part_offset=8388608, part_size=3000579915776, sector_size=512
NTFS partition cannot be added (part_offset<part_size).
NTFS at 1/5/5
Warning: number of bytes per sector mismatches 4096 (NTFS) != 512 (HD)
filesystem size           732563456
sectors_per_cluster       1
mft_lcn                   786432
mftmirr_lcn               366281727
clusters_per_mft_record   1
clusters_per_index_record 1
     MS Data                    16384 5860524031 5860507648
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
NTFS at 16/113/34
filesystem size           5860268032
sectors_per_cluster       8
mft_lcn                   786432
mftmirr_lcn               2
clusters_per_mft_record   -10
clusters_per_index_record 1
NTFS part_offset=135266304, part_size=3000457232384, sector_size=512
NTFS partition cannot be added (part_offset<part_size).
NTFS at 16/113/34
filesystem size           5860268032
sectors_per_cluster       8
mft_lcn                   786432
mftmirr_lcn               2
clusters_per_mft_record   -10
clusters_per_index_record 1
     MS Data                   264192 5860532223 5860268032
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
Search for partition aborted
Results
     MS Data                    16384 5860524031 5860507648
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
     MS Data                   264192 5860532223 5860268032
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
     MS Data                    16384 5860524031 5860507648
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
Can't open filesystem. Filesystem seems damaged.
dir_partition inode=5
     MS Data                   264192 5860532223 5860268032
     NTFS, blocksize=4096, 3000 GB / 2794 GiB
Directory /
       5 dr-xr-xr-x     0      0         0  1-Aug-2015 09:17 .
       5 dr-xr-xr-x     0      0         0  1-Aug-2015 09:17 ..
      36 dr-xr-xr-x     0      0         0 15-Jun-2015 22:40 $RECYCLE.BIN
  354052 dr-xr-xr-x     0      0         0 14-Feb-2015 16:29 AVCHD
   76246 dr-xr-xr-x     0      0         0  6-Feb-2015 07:44 AndroidApps
   30657 dr-xr-xr-x     0      0         0  8-Jun-2014 17:56 Digital Multimeter Tutorials
  242157 dr-xr-xr-x     0      0         0 26-Jun-2015 22:28 KindleBWWS
     468 dr-xr-xr-x     0      0         0 27-Jun-2015 20:23 Maximus_V_Extreme
  356180 dr-xr-xr-x     0      0         0 14-Feb-2015 19:54 Media
  349565 dr-xr-xr-x     0      0         0 13-Feb-2015 07:58 Mondieu
   17724 dr-xr-xr-x     0      0         0 24-Jan-2014 17:03 StockPhotos
      39 dr-xr-xr-x     0      0         0  2-Feb-2014 05:51 System Volume Information
  356251 dr-xr-xr-x     0      0         0  4-Jul-2015 02:17 Websites
   13667 dr-xr-xr-x     0      0         0 16-Nov-2014 22:24 WorkingDocs
      42 dr-xr-xr-x     0      0         0 24-Jan-2015 12:07 dwhelper
     459 dr-xr-xr-x     0      0         0 12-Feb-2015 12:41 wamp
  345103 -r--r--r--     0      0       542 11-Aug-2004 20:20 Sample Music.lnk
     502 -r--r--r--     0      0    242176  7-Nov-2007 07:53 VC_RED.MSI
     504 -r--r--r--     0      0   1927956  7-Nov-2007 07:50 VC_RED.cab
     491 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.1028.txt
     492 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.1031.txt
     493 -r--r--r--     0      0     10134  7-Nov-2007 07:00 eula.1033.txt
     495 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.1036.txt
     496 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.1040.txt
     497 -r--r--r--     0      0       118  7-Nov-2007 07:00 eula.1041.txt
     498 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.1042.txt
     490 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.2052.txt
     494 -r--r--r--     0      0     17734  7-Nov-2007 07:00 eula.3082.txt
			
			
									
						
										
						Seagate 3TB bad GPT partition, invalid header
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Before posting, please read https://www.cgsecurity.org/testdisk.pdf
	When asking for technical support:
- Search for posts on the same topic before posting a new question.
- Give clear, specific information in the title of your post.
- Include as many details as you can, MOST POSTS WILL GET ONLY ONE OR TWO ANSWERS.
- Post a follow up with a "Thank you" or "This worked!"
- When you learn something, use that knowledge to HELP ANOTHER USER LATER.
Before posting, please read https://www.cgsecurity.org/testdisk.pdf