Fixing corrupted ogg files

I have several corrupted ogg files; I believe they were created several 
years ago with grip, and that the corruption is not disk corruption but 
just something wrong with the encoder at the time. I would rather not 
have to re-rip these discs.

The error I see with ogginfo is

Warning: Hole in data (18000 bytes) found at approximate offset 
702086827724505088 bytes. Corrupted ogg.
Warning: Hole in data (22500 bytes) found at approximate offset 
702086827724505088 bytes. Corrupted ogg.
[etc., and then:]
Warning: sequence number gap in stream 1. Got page 4 when expecting page 
1. Indicates missing data.
Warning: discontinuity in stream (1)
Warning: Could not decode vorbis header packet 1 - invalid vorbis stream (1)
[...]
Vorbis stream 1:
         Total data length: 0 bytes
         Playback length: 0m:00.000s
         Average bitrate: nan kb/s
Logical stream 1 ended

I've googled around for an ogg corruption fixer but there doesn't seem 
to be anything out there. I've tried rewriting them with mencoder and 
ffmpeg, but it doesn't make any difference (and I see similar errors 
during the rewrite).

Is there really no tool to repair corrupted ogg files? Would just 
removing the header possibly fix the problem? If so, how would I do 
that? Any other suggestions?

Thanks,

Adam