RAID1 all bootable

Hi:
With a raid1 amd64 wheezy, one of the two HDs got broken.
Unfortunately, I had added grub to sda only, which is just the one
broken. So that, when it is replaced with a fresh HD, the OS is not
found. Inverting the SATA cables of course does not help (Operative
System Not Found). In a previous similar circumstance, I was lucky
that the broken HD was the one without gru.

Is any way to recover? perhaps through Knoppix? I know how to look
into undamaged RAID1 with Knoppix.

Also, when making a fresh RAID1 from scratch, where to find a Debian
description  of how to make both sda and sdb bootable? (which should
be included by default, in my opinion)

Thanks
francesco pietra