I think a little more history may be required, before you say that JFS may be a problem. It is known, that the older JFS did have some major problems, and what you are seeing, *may* be the result, if you did not reformat the volume, when the fix was made, after you did the update (this all happened a few years ago, so I don't remember the details). The "new " JFS (the bootable one), seems to be rock solid, for me (perhaps I have just been lucky). It can also be developed further, since they have the source, which is not true of the older IBM version.
On the other hand, you say that there was a bad sector. Depending on, exactly, where that sector is, and what was wrong with it, it may have taken out part of the stuff that is required to be able to recover anything. That is a hardware problem, and can happen to any file system, although a RAID system is supposed to be able to recover from that sort of thing. I do hope, that you replaced that disk, since one bad sector is a warning, that more may happen (may not too). At least you had a good backup, which is really the only recovery for hardware problems (and other things) on a disk drive.