Well, first of all, thanks for the tip about the 12 volt battery. I've been using my 6-volt and the light is so weak I can't see anything. Now, here is the problem I am having: looking at your photo here I see a metallic colored plate between the green base and black distributor which the manual calls the advance arm. As you said, there is a bolt on the side and another bolt and nut to loosen. When I loosen both of these, and even if I disconnect the vacuum advance, I can only move the advane arm itself back and forth, I cannot turn the actual distributor, and I have been afraid to twist too hard and break something.
One more thing: on my car the advance arm is positioned 180 degrees from yours, i.e. the side with the bolt faces more towards the left side of the car (yours faces more toward the right side).
Finally, when I decelerate from highway speeds backfiring occurs. Could these be due to the timing or is the carburetor more likely?
Thanks for the picture and advice--I'm still trying to figure this out.