(1+2) + pin
The aperture linkage(black clip pin) is installed, then glues
the whole block in the previous photo (P35m_27) to this.

This pin catches the small cut on the lens block (P35m_21),
Rokkor's helicoid extends 7mm, so the pin should be long.
(But not too long in order to avoid hitting the optical block
at its infinity position. If it hits, cut the the tip of this pin.)

When you glue the whole thing in P35m_27 to this Rokkor's
LBH, careful to position it for the aperture's moving range.