just got a protractor head, when i look at the degree scale with the locking nut facing up, everything lines up properly. seen here:
100_5131.jpg
When i rotate the locking nut to facing down, the marks DO NOT line up properly, they look like they are off 1 or 1.5 degrees. seen here:
100_5130.jpg
Why is that, why does rotating it seem to make it read differently?