UPDATE:
I am now certain that the clickstop (spring loaded steel ball) is the part which went awry.
Shown below is the enlarger assembled as far as I was able to do it. The spring is actually inside the red box area and fits the steel ball nicely when compressed.
Documentation suggests that the spring loaded steel ball goes into the red box area, and the screw to hold it onto the spring goes into the blue box area. Below are the said steel ball and spring which fall onto my easel when I was disassembling the unit.
When I thread on the lens mounting piece identified as "A" in the picture below I cannot seem to thread it on all the way shown by the threads still being clearly visible. But if I thread on piece A while the enlarger arm is at its lowest height I can get it to look like the second picture threading it further.
Even if I could adjust manual focus on the enlarger, which I cannot, because the helical just spins without raising or lowering the lens, the lens gets nowhere near close enough to the film to allow the image to come into focus. Below I've show a picture of the film being projected onto a piece of paper held about 4 inches off the enlarger base to try to close the gap between the lens and the paper.