pg_class.relnamespace NOT IN pg_namespace.oid

Hello,

It apperas that I have some entries in pg_class that have relnamespace not appearing in
pg_namespace. So pg_dump fails with "pg_dump: schema with OID 52072764 does not exist", I guess.
Like the schema in question was dropped, but not cascading to all its members?

How to get rid of or fix these damaged entries? Just try to delete from pg_class manually (and then
delete files pointed to by their relfilenode)? Or create a new schema and update
pg_class.relnamespace to the oid of the new schema and then inspect and drop? Or any other
higher-level tools?

Server version is 8.4.9.

Thanks

Irek.