I had some trouble with my CA18 spigot when i went to bolt the gearbox up to my new motor and realised it didn't have a spigot in there.. I went and bought a ca18 manual spigot bush from my local brake and clutch shop and when i got it back it looked like it was too big to fit..
I then realised that the new motor did have a spigot, but it wasn't a small brass one like i was expecting, it was a large steel one of about 35-40mm outside diameter and the inside diameter was just smaller than the outside diameter of the brass spigot i had bought. It was possibly the auto spigot?? i dont really know.. All i know is that it was a complete bit** to remove!
In the end i sacrificed my steering wheel puller and welded it to the spigot and finally it popped out and i was able to fit the little brass sucker in behind where the old spigot was located...
I dont know if its the same problem your encountering but i hope it helps,
Mark.
also, i was told its a good idea to soak the brass spigot bushes in motor oil for a good few hours or more before fitting them as they are porous and soak up the oil. It made fitting mine pretty easy anyway..