SLES11 - RAID6 all disks marked as Spare

Hello,

After a replacement of the motherboard of my server, all disks belonging to a raid6 are now marked as spare.

Is there any way to mark those disks as active and restore the raid6?

$ cat /proc/mdstat 
Personalities : [raid1] [raid0] [raid6] [raid5] [raid4] 
md1 : inactive sda1[1](S) sdk1[11](S) sdj1[10](S) sdi1[9](S) sdh1[8](S) sdg1[7](S) sdf1[6](S) sde1[5](S) sdd1[4](S) sdc1[3](S) sdb1[2](S)
      10744359296 blocks
       
md0 : active raid1 sdm1[0] sdn1[1]
      2096384 blocks [2/2] [UU]
      
md2 : active raid1 sdm3[0] sdn3[1]
      104864192 blocks [2/2] [UU]
      
unused devices: <none>

All disks show the same info:

$ mdadm -E /dev/sdb1 
/dev/sdb1:
          Magic : a92b4efc
        Version : 0.90.00
           UUID : d293389b:7b11f66f:33b8bc9f:5417f8db
  Creation Time : Tue Dec  9 20:52:05 2008
     Raid Level : raid6
  Used Dev Size : 976759936 (931.51 GiB 1000.20 GB)
     Array Size : 9767599360 (9315.11 GiB 10002.02 GB)
   Raid Devices : 12
  Total Devices : 12
Preferred Minor : 1

    Update Time : Wed Jun  3 09:34:06 2009
          State : active
Active Devices : 12
Working Devices : 12
Failed Devices : 0
  Spare Devices : 0
       Checksum : 4c480fd3 - correct
         Events : 505329

     Chunk Size : 128K

      Number   Major   Minor   RaidDevice State
this     1       8       17        1      active sync   /dev/sdb1

   0     0       8        1        0      active sync   /dev/sda1
   1     1       8       17        1      active sync   /dev/sdb1
   2     2       8       33        2      active sync   /dev/sdc1
   3     3       8       49        3      active sync   /dev/sdd1
   4     4       8       65        4      active sync   /dev/sde1
   5     5       8       81        5      active sync   /dev/sdf1
   6     6       8       97        6      active sync   /dev/sdg1
   7     7       8      113        7      active sync   /dev/sdh1
   8     8       8      129        8      active sync   /dev/sdi1
   9     9       8      145        9      active sync   /dev/sdj1
  10    10       8      161       10      active sync   /dev/sdk1
  11    11       8      177       11      active sync   /dev/sdl1

UUID of all disks are the same as in mdadm.conf