[ADMIN] pg_dump ERROR: missing chunk number 0 for toast value

I'm using PostgreSQL 9.3.16 on Windows 7 and the data directory was created from a filesystem backup of an installation
runningon another machine, which failed. 

After starting the postgres service I ran `pg_dump` using pgAdminIII to backup the databases.

    pg_dump.exe --host localhost --port 5433 --username "postgres" --no-password  --format custom --blobs --verbose
--file"db-2017-03-22.backup" "mydb" 

One of them reported the following error:

    pg_dump: dumping contents of table "public.bandana"
    pg_dump: dumping contents of table "public.bodycontent"
    pg_dump: Dumping the contents of table "bodycontent" failed: PQgetResult() failed.
    pg_dump: Error message from server: ERROR:  missing chunk number 0 for toast value 314936 in pg_toast_36791
    pg_dump: The command was: COPY public.bodycontent (bodycontentid, body, contentid, bodytypeid) TO stdout;

    Process returned exit code 1.

Since then I've done some digging around and run the following commands:

    REINDEX table pg_toast.pg_toast_36791;
    VACUUM ANALYZE bodycontent;

Both return:

    Query returned successfully with no result in xx ms.

Using pgAdmin I've selected the Maintenace option and run a VACUUM (no options) , ANALYSE and REINDEX and no errors
werereported. 

I ran VACUUM with the FULL option and the following error was reported:

    INFO:  vacuuming "public.plugindata"
    ERROR:  missing chunk number 0 for toast value 289849 in pg_toast_36998

I don't have any experience with postgres or databases in general. Can anyone advise what I should do next?