The enlarged top view suggests that it was designed so the spindle could be aligned at the workbench. On the card, the cardinal points would be diagonal lines at the four corners. At each corner, the distance from the spindle is great enough to get a reading with the head or tail.
With the head on each cardinal point, the tail should be precisely over the opposite. If when the head is on 0 the tail is on 181, try the head on 180. If the tail is on 1, you need to take the arrow off and straighten it. If the tail is on 359, you need to need to tip the brass post east, perhaps as far as the thickness of two sheets of paper. You would do this by removing the arrow and using a punch to hit the east arm of the cross. In the photo, it looks as if N,S, and W have already been hit.
In the photo it's easy to see that the camera is not aligned over the tail vane. It would be even easier if the top edge were polished bright yellow.
I'd love to own one! I wonder if Harbor Freight has any Chinese knockoffs.