Corrupted UFS2 file system?

I use rsync to update a backup disk on a server. For a few months I have
been getting errors for a few lost+found files. I have done "ls -l -o" and
found many system flags are set on the files. Attempting to modify the
files as root fails:
# chflags 0 #31232359
chflags: #31232359: Operation not supported

This is clearly a corruption. All three files show a bad creation date (Dec
22  1971) and a size of 4096. All include the flags sappnd, schg, sunlnk,
snapshot, hidden, uunlnk, rdonly, and system. I suspect that snapshot
prevents me from doing anything to the files, but I have no idea how I
might fix this. Full fsck finds no errors. SMART shows a past error, but o
current ones.

Any clue as to how this might be fixed other than reinitialising the
partition and starting from scratch?
-- 
Kevin Oberman, Part time kid herder and retired Network Engineer
E-mail: rkoberman@gmail.com
PGP Fingerprint: D03FB98AFA78E3B78C1694B318AB39EF1B055683