Comment # 7 on bug 1156073 from T Adams

Neil and Michael, thanks once more for your efforts to help.  

Fortunately, I can get into the system, after locking the grub files named in
the second post in this thread, above.  FWIW, my current grub2 version is
2.02-50.1.

For Neil:

Yast --> Boot Loader --> Boot Loader Location --> Boot from Partition is
checked.  Also checked on this same screen are "Set active Flag in Partition
Table for Boot Partition" and "Write generic Boot Code to MBR."

For Michael:

cat /etc/default/grub_installdevice

/dev/disk/by-uuid/452bcebb-fb29-448f-81c0-70397fcf1274
activate
generic_mbr

# hexdump -n 512 -C /dev/sda
00000000  eb 63 90 8e d8 8e d0 bc  00 7c 89 e6 06 57 8e c0  |.c.......|...W..|
00000010  fb fc bf 00 06 b9 00 01  f3 a5 ea 1f 06 00 00 52  |...............R|
00000020  52 b4 41 bb aa 55 31 c9  30 f6 f9 cd 13 72 13 81  |R.A..U1.0....r..|
00000030  fb 55 aa 75 0d d1 e9 73  09 66 c7 06 8d 06 b4 42  |.U.u...s.f.....B|
00000040  eb 15 5a b4 08 cd 13 83  e1 3f 51 0f b6 c6 40 f7  |..Z......?Q...@.|
00000050  e1 52 50 66 31 c0 66 99  e8 66 00 80 01 00 00 00  |.RPf1.f..f......|
00000060  00 00 00 00 ff fa 90 90  f6 c2 80 74 05 f6 c2 70  |...........t...p|
00000070  74 02 b2 80 ea 79 7c 00  00 31 c0 8e d8 8e d0 bc  |t....y|..1......|
00000080  00 20 fb a0 64 7c 3c ff  74 02 88 c2 52 be 80 7d  |. ..d|<.t...R..}|
00000090  e8 17 01 be 05 7c b4 41  bb aa 55 cd 13 5a 52 72  |.....|.A..U..ZRr|
000000a0  3d 81 fb 55 aa 75 37 83  e1 01 74 32 31 c0 89 44  |=..U.u7...t21..D|
000000b0  04 40 88 44 ff 89 44 02  c7 04 10 00 66 8b 1e 5c  |.@.D..D.....f..\|
000000c0  7c 66 89 5c 08 66 8b 1e  60 7c 66 89 5c 0c c7 44  ||f.\.f..`|f.\..D|
000000d0  06 00 70 b4 42 cd 13 72  05 bb 00 70 eb 76 b4 08  |..p.B..r...p.v..|
000000e0  cd 13 73 0d 5a 84 d2 0f  83 d8 00 be 8b 7d e9 82  |..s.Z........}..|
000000f0  00 66 0f b6 c6 88 64 ff  40 66 89 44 04 0f b6 d1  |.f....d.@f.D....|
00000100  c1 e2 02 88 e8 88 f4 40  89 44 08 0f b6 c2 c0 e8  |.......@.D......|
00000110  02 66 89 04 66 a1 60 7c  66 09 c0 75 4e 66 a1 5c  |.f..f.`|f..uNf.\|
00000120  7c 66 31 d2 66 f7 34 88  d1 31 d2 66 f7 74 04 3b  ||f1.f.4..1.f.t.;|
00000130  44 08 7d 37 fe c1 88 c5  30 c0 c1 e8 02 08 c1 88  |D.}7....0.......|
00000140  d0 5a 88 c6 bb 00 70 8e  c3 31 db b8 01 02 cd 13  |.Z....p..1......|
00000150  72 1e 8c c3 60 1e b9 00  01 8e db 31 f6 bf 00 80  |r...`......1....|
00000160  8e c6 fc f3 a5 1f 61 ff  26 5a 7c be 86 7d eb 03  |......a.&Z|..}..|
00000170  be 95 7d e8 34 00 be 9a  7d e8 2e 00 cd 18 eb fe  |..}.4...}.......|
00000180  47 52 55 42 20 00 47 65  6f 6d 00 48 61 72 64 20  |GRUB .Geom.Hard |
00000190  44 69 73 6b 00 52 65 61  64 00 20 45 72 72 6f 72  |Disk.Read. Error|
000001a0  0d 0a 00 bb 01 00 b4 0e  cd 10 ac 3c 00 75 f4 c3  |...........<.u..|
000001b0  00 00 00 00 00 00 00 00  59 f4 8a dd b8 ed 00 20  |........Y...... |
000001c0  21 00 07 df 13 0c 00 08  00 00 00 20 03 00 00 df  |!.......... ....|
000001d0  14 0c 07 7b 48 73 00 28  03 00 00 38 f4 13 80 fe  |...{Hs.(...8....|
000001e0  ff ff 83 fe ff ff 00 60  f7 13 b0 d2 d7 09 00 00  |.......`........|
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 aa  |..............U.|
00000200

# lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sda      8:0    0 238.5G  0 disk 
������sda1   8:1    0   100M  0 part 
������sda2   8:2    0 159.6G  0 part 
������sda3   8:3    0  78.8G  0 part /
sdb      8:16   0   1.8T  0 disk 
������sdb1   8:17   0   128M  0 part 
������sdb2   8:18   0   1.8T  0 part 
sdc      8:32   0   1.8T  0 disk 
������sdc1   8:33   0   128M  0 part 
������sdc2   8:34   0   1.8T  0 part 
sr0     11:0    1  1024M  0 rom  

A second FWIW: sda1 and sda2 are Windows 7.  Tumbleweed is installed on sda3
without a swap partition.  sdb and sdc are encrypted data drives.  

The hexdumps for /dev/sdb and /dev/sdc: 

# hexdump -n 512 -C /dev/sdb
00000000  33 c0 8e d0 bc 00 7c 8e  c0 8e d8 be 00 7c bf 00  |3.....|......|..|
00000010  06 b9 00 02 fc f3 a4 50  68 1c 06 cb fb b9 04 00  |.......Ph.......|
00000020  bd be 07 80 7e 00 00 7c  0b 0f 85 0e 01 83 c5 10  |....~..|........|
00000030  e2 f1 cd 18 88 56 00 55  c6 46 11 05 c6 46 10 00  |.....V.U.F...F..|
00000040  b4 41 bb aa 55 cd 13 5d  72 0f 81 fb 55 aa 75 09  |.A..U..]r...U.u.|
00000050  f7 c1 01 00 74 03 fe 46  10 66 60 80 7e 10 00 74  |....t..F.f`.~..t|
00000060  26 66 68 00 00 00 00 66  ff 76 08 68 00 00 68 00  |&fh....f.v.h..h.|
00000070  7c 68 01 00 68 10 00 b4  42 8a 56 00 8b f4 cd 13  ||h..h...B.V.....|
00000080  9f 83 c4 10 9e eb 14 b8  01 02 bb 00 7c 8a 56 00  |............|.V.|
00000090  8a 76 01 8a 4e 02 8a 6e  03 cd 13 66 61 73 1c fe  |.v..N..n...fas..|
000000a0  4e 11 75 0c 80 7e 00 80  0f 84 8a 00 b2 80 eb 84  |N.u..~..........|
000000b0  55 32 e4 8a 56 00 cd 13  5d eb 9e 81 3e fe 7d 55  |U2..V...]...>.}U|
000000c0  aa 75 6e ff 76 00 e8 8d  00 75 17 fa b0 d1 e6 64  |.un.v....u.....d|
000000d0  e8 83 00 b0 df e6 60 e8  7c 00 b0 ff e6 64 e8 75  |......`.|....d.u|
000000e0  00 fb b8 00 bb cd 1a 66  23 c0 75 3b 66 81 fb 54  |.......f#.u;f..T|
000000f0  43 50 41 75 32 81 f9 02  01 72 2c 66 68 07 bb 00  |CPAu2....r,fh...|
00000100  00 66 68 00 02 00 00 66  68 08 00 00 00 66 53 66  |.fh....fh....fSf|
00000110  53 66 55 66 68 00 00 00  00 66 68 00 7c 00 00 66  |SfUfh....fh.|..f|
00000120  61 68 00 00 07 cd 1a 5a  32 f6 ea 00 7c 00 00 cd  |ah.....Z2...|...|
00000130  18 a0 b7 07 eb 08 a0 b6  07 eb 03 a0 b5 07 32 e4  |..............2.|
00000140  05 00 07 8b f0 ac 3c 00  74 09 bb 07 00 b4 0e cd  |......<.t.......|
00000150  10 eb f2 f4 eb fd 2b c9  e4 64 eb 00 24 02 e0 f8  |......+..d..$...|
00000160  24 02 c3 49 6e 76 61 6c  69 64 20 70 61 72 74 69  |$..Invalid parti|
00000170  74 69 6f 6e 20 74 61 62  6c 65 00 45 72 72 6f 72  |tion table.Error|
00000180  20 6c 6f 61 64 69 6e 67  20 6f 70 65 72 61 74 69  | loading operati|
00000190  6e 67 20 73 79 73 74 65  6d 00 4d 69 73 73 69 6e  |ng system.Missin|
000001a0  67 20 6f 70 65 72 61 74  69 6e 67 20 73 79 73 74  |g operating syst|
000001b0  65 6d 00 00 00 63 7b 9a  00 00 00 00 00 00 00 00  |em...c{.........|
000001c0  02 00 ee ff ff ff 01 00  00 00 ff ff ff ff 00 00  |................|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 aa  |..............U.|
00000200

# hexdump -n 512 -C /dev/sdc
00000000  33 c0 8e d0 bc 00 7c 8e  c0 8e d8 be 00 7c bf 00  |3.....|......|..|
00000010  06 b9 00 02 fc f3 a4 50  68 1c 06 cb fb b9 04 00  |.......Ph.......|
00000020  bd be 07 80 7e 00 00 7c  0b 0f 85 0e 01 83 c5 10  |....~..|........|
00000030  e2 f1 cd 18 88 56 00 55  c6 46 11 05 c6 46 10 00  |.....V.U.F...F..|
00000040  b4 41 bb aa 55 cd 13 5d  72 0f 81 fb 55 aa 75 09  |.A..U..]r...U.u.|
00000050  f7 c1 01 00 74 03 fe 46  10 66 60 80 7e 10 00 74  |....t..F.f`.~..t|
00000060  26 66 68 00 00 00 00 66  ff 76 08 68 00 00 68 00  |&fh....f.v.h..h.|
00000070  7c 68 01 00 68 10 00 b4  42 8a 56 00 8b f4 cd 13  ||h..h...B.V.....|
00000080  9f 83 c4 10 9e eb 14 b8  01 02 bb 00 7c 8a 56 00  |............|.V.|
00000090  8a 76 01 8a 4e 02 8a 6e  03 cd 13 66 61 73 1c fe  |.v..N..n...fas..|
000000a0  4e 11 75 0c 80 7e 00 80  0f 84 8a 00 b2 80 eb 84  |N.u..~..........|
000000b0  55 32 e4 8a 56 00 cd 13  5d eb 9e 81 3e fe 7d 55  |U2..V...]...>.}U|
000000c0  aa 75 6e ff 76 00 e8 8d  00 75 17 fa b0 d1 e6 64  |.un.v....u.....d|
000000d0  e8 83 00 b0 df e6 60 e8  7c 00 b0 ff e6 64 e8 75  |......`.|....d.u|
000000e0  00 fb b8 00 bb cd 1a 66  23 c0 75 3b 66 81 fb 54  |.......f#.u;f..T|
000000f0  43 50 41 75 32 81 f9 02  01 72 2c 66 68 07 bb 00  |CPAu2....r,fh...|
00000100  00 66 68 00 02 00 00 66  68 08 00 00 00 66 53 66  |.fh....fh....fSf|
00000110  53 66 55 66 68 00 00 00  00 66 68 00 7c 00 00 66  |SfUfh....fh.|..f|
00000120  61 68 00 00 07 cd 1a 5a  32 f6 ea 00 7c 00 00 cd  |ah.....Z2...|...|
00000130  18 a0 b7 07 eb 08 a0 b6  07 eb 03 a0 b5 07 32 e4  |..............2.|
00000140  05 00 07 8b f0 ac 3c 00  74 09 bb 07 00 b4 0e cd  |......<.t.......|
00000150  10 eb f2 f4 eb fd 2b c9  e4 64 eb 00 24 02 e0 f8  |......+..d..$...|
00000160  24 02 c3 49 6e 76 61 6c  69 64 20 70 61 72 74 69  |$..Invalid parti|
00000170  74 69 6f 6e 20 74 61 62  6c 65 00 45 72 72 6f 72  |tion table.Error|
00000180  20 6c 6f 61 64 69 6e 67  20 6f 70 65 72 61 74 69  | loading operati|
00000190  6e 67 20 73 79 73 74 65  6d 00 4d 69 73 73 69 6e  |ng system.Missin|
000001a0  67 20 6f 70 65 72 61 74  69 6e 67 20 73 79 73 74  |g operating syst|
000001b0  65 6d 00 00 00 63 7b 9a  00 00 00 00 00 00 00 00  |em...c{.........|
000001c0  02 00 ee ff ff ff 01 00  00 00 ff ff ff ff 00 00  |................|
000001d0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
000001f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 55 aa  |..............U.|
00000200