On a Pantera rack the cup/nut are threaded on to the toothed portion. The nut is a lock nut and the cup can be tightened to pretension the ball so that it just holds in place under it's own weight. I would be surprised if there is no similar form of adjustemnt on this rack too.
Julian
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.