I expanded the entry and boom, the piece fit. I did not need to do any manipulation of the optics. Quite a nice surprise.
The scanner is glued in. I used sprue-goo because it is thick. Thus, it allowed me to control where the glue goes. No capillary action to worry about with that stuff.
My finger. Premature camera trigger.
From here I will light-block internals of the scanner, then start remaking the rest of the optics.