Thank you all for the feedback
That green tube is the insulation from the copper wire. FSM run a good article on motorizing props in their Jan 2003 issue. That's where I got most of my ideas, including the wire insulation. Ironically, I ended up removing the insulation and replaced it with a straight brass tube that runs directly to the motor. Got rid of the aluminium guiding ring, too. Runs much better. That last picture happened by chance and I tried to replicate the settings since but no such luck. I am working on a web site with all the info I can put together about motorizing propellers. The first time I saw a motorized prop I knew my own prop planes would never be the same.
Borislav