That and how they go about setting the proper height.
The directions say to use the three "flat pads"... by doing this the one rca connector is inaccessable.
Why not put a shoulder on the mounting sleeve?
Or make it so three dowels, evenly spaced on the diameter, fit into a mating surface on the base? This would establish height, maintain the arm assembly square to the base and fix the orientation. Then use the set screw.
The Germans got lazy with this design.