I don't know if linux supports the new Amiga file systems, but if it does you could always put the disk in a linux box and use linux disk utils on it. This should really be a last resort. It might work. It might ruin your disk. Don't blame me. :-)
Doesn't OS3.9 come with some kind of disk repair utility? Seems kinda odd to develop an extension of FFS and not supply the proper tools for it...
