Postgres Crash! Need help on recovery


My RT 2.0.15 is down since yesterday. When I try any query in the database
from the table attachments, I get:

tickets=# select * from attachments;
ERROR: cannot open attachments_pkey: No such file or directory

Also, this query came up with duplicates, for 884 < id < 908 (my current
id sequence is at 11533).

tickets=# select * from (select count(id) as q, id from attachments group by
id) as foo where q > 1;

Database is postgres 7.2.3 (RHDB 2.1), running on Redhat 7.3 (fully up2dated).

I need some help on recovering my RT installation. I guess I can dump the
database one table at a time and recreate elsewhere, but what do I do for
the attachments table? Can I drop the primary key for attachments table
(temporarily, till I pg_dump the data)? ALTER TABLE DROP PRIMARY KEY doesn’t
work. I can get a newer version of postgres installed, if needed.