Hi,
Just a guess, but if you used one of the database vendor's tools to delete the "JTX_" tables and feature classes, this may have corrupted the SDE system tables and introduced the error you're seeing below. In general, it's a best practice to only use ArcCatalog, ArcMap, a GP tool, etc. to create/delete items in an SDE geodatabase.
Regardless of how the tables were deleted, a simple test would be to create a new database and run the WMX post-install on that DB. If this is successful and there's other (non-WMX-related) information in the old DB that you need to preserve, you could try copying only those feature classes & tables to the new DB using ArcCatalog, or restoring the old DB from a backup.
I hope this helps; good luck!
Brian D.