@Lucky2
Len, I assume it is the relatively new PSI kit ... on their website as "Duraclick EDC" .... weird name .... EDC means "Everyday Carry".
@mark james
Mark, I don't think there is anything unusual about the assembly. . Just be sure that the button click mechanism is NOT screwed into the finial when you are pressing together.
I guess it's possible you might be making the "Everyday Classic" .... an even newer kit, with another weird name and source of confusion possibly.
If this is your pen, then the mechanism is pre-assembled but without the push button. . Just leave it that way and fit the button after pressing.
I think the instructions for both kits are quite explicit and accurate.