The fact that the crown race seat measures 26.1 to 26.3 is a concern.

The crown race is an interference fit and the crown race seat on the fork is supposed to be slightly larger than the crown race itself.

IIRC a 26.4 mm crown race requires a 26.5 mm crown race seat. Please confirm this.

This may explain why it is knurled. Someone may have tried to increase the size.