SWAG once you remove the dust cap you'll be able to access the cone's inner flat to lock in the proper tension. Or discover it takes "a special too." The dust cap must be replaceable last, after the rebuild is complete.
With an older Record hub, the dust cap goes in place before all that, which is possible because both flats are exposed.
I presume a wrench on each lock nut will allow you to take these apart in order to see what's really happening. Never worked on one, myself.
Good luck!