So it seems like I didn't do the grub sync to boot from booth disks.
When the new install done check the disk syncs.
When the disks syncs done(cat /proc/mdstat) run the grub.
>grub: root (hd0,0)
>grub: setup (hd0)
>grub: root (hd1,0)
Change the defect device. (hw setup)
run the mdadm --manage /dev/md0 --add /dev/sdb1
mdadm --manage /dev/md1 --add /dev/sdb2
cat /proc/mdstat recovery = 55% wait for sync then repeat the grub sync!!!!
I'll check it how it goes cos I'm not sure about the superblock, and sfdisk too.
Some page said needs to copy partitions and some page does not.