Hmm, in my haste I forgot a step …
The front consists of two plates, instead of one.
The first one holds the two dials … and underneath that is the main front plate that holds the lens and gears. I forgot about that and forgot about the first plate.
So the first plate is screwed onto the second.
This is what happens when I take everything apart and try to explain it in reverse … or at partial stages when I have to take it apart again because I missed something.