Here are the photos;
It is the best I can do to explain how it works.
Yes you can spin the drum from the outside of the cabinet.
It is not binding in any way at all.
When you roll the drum it is connected to the tuning capacitor and the tuning capacitor turns also.
The plastic is painted on the inside of the drum.
It is not a good system. I do have that same information from Pacific TV
Dan in Calgary