Santiago, your work is superb as always! I am in awe of your ability to dive right into such projects to improve, detail and refinish your locos and rolling stock. 
I wanted to mention a couple of issues I've had with the drive tower you're using because it might prevent the loco from reaching the same level of perfection in operation. Both are in the crop of your picture below.
The red oval outlines the downward angle of the top shaft which results in the chain dragging as it leaves the sprocket teeth at an angle. The green arrow shows where the sides of the chain links extend beyond the sprocket boss and can catch on the large washer as they pass. These two combine to create drag, noise and vibration that can spoil the smooth running.
I learned about this from Bob Sobol's work but lacking his skills and equipment, I went with the Finescale 360 adustable tower and ball-bearing shaft kit. I saw that used successfully by MaxSouthOz in a thread here:
https://ogrforum.ogaugerr.com/...first-attempt?page=1
Pete
