Take out the allen head screw from the adapter nut. It looks like it is in too far and hitting the crankshaft thus not allowing the nut to seat properly. Based upon your post, it seems that the help off an experienced pilot/builder/engine guru onsite to help would be your best bet if possible. They would be able to show you how to setup everything correctly. They should be able to show you how to balance your prop correctly as well. MAS props are rarley ever balanced right out of the bag.