recover as much as possible (xlog flush request not satisfied)

I have a postgres db version 8.2.15 (Yes, I know it's rather old version).
After correcting some disk and file system problems the postgres table seems to be corrupt, returning:

ERROR: xlog flush request B67/44479CB8 is not satisfied --- flushed only to B67/429EB150

CONTEXT: writing block 33652 of relation 1663/18776/21757

on a simple select statement.
What is the best way to get past this?
I'm happy if I can recover 80 or 90% of the database.
Unfortunately, there are no dumps/backups available.

Can you give some pointers to extract as much data as possible out of the database?
How difficult would it be to extract data directly from the files containing the data?
(FYI: the fields used in the most important table are: bigint, character varying(32), character(1), integer, smallint, text)

Regards,
Wim Goedertier