The technical parts of the upper reactor are painted black (citadel spray can), then it is installed in the slot without gluing.

all the wires are all soldered together. Luckily there is a lot of room inside the model to fit the big spaghetti plate !

You can see that an optical fiber had broke during these manipulations. I hope it will still light correctly with a transparent plastic cap glued on...

Little tests with the nozzles dry installed

Given the poor seams, I expected to have lot's of light leakage, and luckily, it is far less serious than I thought, and only focused on the round nozzles bases.

For 2 below nozzles, a spare tube is added, and this completely solves the problem at this level (even without gluing the nozzles)

For the top one, the back disk and the flange are completed and then covered with black paint.

These tips are sufficient to solve the problem of light leaks, so I will finally not glue these two parts (upper engine and nozzles), in case I need to have hand in the future.

Some seams will then stay as is but should remain little viewable in the end (I think the eye will ignore them).

The plug is more firm as I expected and perfectly fulfill its second office : support. Even upside down, it works :)