WW 2.4 seems to work now. I dropped the entire webwork database on the new install and created the database anew. Then created admin course. Imported old courses' tables, wwdb_check, wwdb_upgrade.
In my previous attempt I imported the entire webwork DB from WW 2.2, deleted old admin_*, created new admin and ran wwdb_check and wwdb_upgrade. This did not work for some reason.