The last task left for Unit Shift was to install (what I call) the buffer valve. I use this term because its purpose is to store the Unit Shift selection (on or off) from the end of the ribbon read (just after the pin jaws close) until the time when the matcase is positioned (just as the matrix jaws close).
The buffer valve is in the right foreground, connected to the Unit Shift valve by three copper tubes. If you want to remove any of this (for instance to adjust the stroke length on the jaws) by far the easiest way is to remove the Unit Shift valve, its buffer valve, bracket and tubing all at once. This is done by removing the two bolts and four screws marked by red arrows (one of the screws is hidden by one of the pipe fittings). All the parts then come off as a unit, connected by the tubing.
The next task is to reinstall the Quadding and Centering actuators on the paper tower.