Hi I recently took the gear selector appart on my 1955 car, on page 170 parts manual there is a hole in the ball piece 500628, the parts manual shows this labelled 1067 where a round headed pin that goes through this about 4 cm long and flattened off to retain in place. With a small file I filled down the edges of the flattened portion and rotated it to do this. Then it can be pulled out and it all comes to pieces.
Alain Sauvage