Fix cards cannot be rotated. That is the purpose of my illustration above..
- I think your picture is not one of those! It looks like a museum piece Narco OBS to me.
Quite honestly fiddling around to allow for fixed card aircraft is a waste of time! Anyone using it should be able to work out their displacement from a line or should not fly IFR. Otherwise how on earth would they cope with tracking a localiser outbound or track away from an NDB?