I just received another flip-flop joystick assembly.(Thanks Chris).
The metal base is two main parts screwed together, and the tension that centers the joystick comes from the leaf switches themselves which have extra metal strips that are somewhat flexible.(I really would like to find out what they are made of).
I don't know what reproducing these would entail, but I can see how it is possible to duplicate the feel of one of these joystick assemblies so that unless you look under the CP, you would not know the original wasn't there.
Once one has the proper sized joystick(which has about a two inch shaft showing beneath the ball-top), it is easy to determine the joystick's axis of rotation.
It is the tension through the joysticks range of motion that one would probably have to work on.(Springs or bushings may or may not work).
Darren Harris
Staten Island, New York.
Searcher7@mail.con2.com