With the spindle vertical and the chuck at the bottom, the full-length slot in the quill must be on the right with the gear rack facing you.
The dog point on the quill lock bolt/handle rides in that quill slot. It would be very apparent if the quill was upside down when the assembly is installed in the head casting.
One more thing... the quill/spindle re-assembly procedure is very different than the larger ball-bearing machines.
That threaded thrust nut is the first part installed on the spindle. Thread that on all the way.
Then slide on the remaining parts.
Tighten the set screw for the upper collar into the divot on the spindle. At this point, the quill will have some vertical movement on the spindle.
Next, back-off the lower thrust nut until the quill has very little vertical movement on the spindle. The quill should turn freely on the spindle.
Lastly, tighten that small set screw in the lower thrust nut against the threads on the spindle thrust collar.
