The vernier will have to be fixed to the top board otherwise you won't be able to make your setting, I can't see the need for any adjustment.
The main azimuth scale will rotate freely on the bottom base (as previously mentioned) until you align your scope to a chosen target. Same as my setup, but replacing my pointer with the vernier. Actually simpler than I originally thought. You will have to fit the vernier by locating the 12mm hole to your M12 pivot bolt, simple.
As I mentioned earlier I will make a set with the vernier located on the inside of the main azimuth scale. The main thing will be to make the main azimuth scale with enough thickness to rub up against the lazy susan without sliding underneath. Also you will need to make your circular cutout around the lazy susan as close as possible and of course concentric with the calibrations and the M12 pivot. I will include a 12mm circle at the centre of the azimuth scale to locate it on the pivot. With the lazy susan fitted on top of the azimuth, use a new sharp blade (surgical blade) you should be able to stab the azimuth scale right up tight against the lazy susan. With the blade held at a slight angle secured into the bottom board and by rotating the free azimuth scale achieve a very accurate fit, this is how I did mine.
A lot of this depends on what type of lazy susan you are using. The one on the lightbridge has two identical round plates located simply with a centre hole. I have seen some lazy susan bearings which are rings not plates, not to sure how easy this type are to fit accurately.
I will post this new set shortly.
Cheers
Richard