There is an extra gear that has a bolt and bushing installed in it that needs to be installed. It should it listed somewhere in the manual, but I haven't looked for it, at work.
Looked at the manual on line here's what it says:
The Gear Box is composed of the change gears, shaft bolt, fixing shaft bolt, and square
nut. The change gear box is fixed on the left support of the leadscrew (101). To cut threads,
select the proper change gears for the desired thread type (see Thread Formula Table), and
engage with approximately 0.1 mm tolerance. Tighten Screw (835).SKU 44859 Page 8
The Fixed Shaft Bolt (825) under the spindle is used for right hand cutting and threading.
The set of Fixed Shaft Bolts in the accessory kit is used in combination with the original set
of Shaft Bolts to reverse the rotation of the long leadscrew for left-handed threading and
cutting.
Look at the section in the manual that has the parts listed in the above specifically 825 and it's associated parts.
Bob