Thanks for the pics and nice to get answers to my theory. It really was just my thinking in case your pin would not budge. Thanks for the offer of the old one, but I won't take it any further at the moment. Now that we know, from your experience, that the pin can be drifted out with reasonable ease, that's what I will do if mine gives trouble, but thanks.
If one had to file or cut the hexagonal peaks off, it looks as if you would have to take the brass peaks down to match the diameter of the round section between the hexagons. It certainly would take quite a bit of time.
Keep us informed on your progress with your Atmo ..... maybe we will see it in Macon next year ferry permitting.
All the best
1990 GTA Atmo, 2003 Jaguar X type 2.5SE Auto, 2002 Daihatsu Sirion 1.3SE