On a side point, "Are you sure" the gauge is accurate?" I don't measure caster by a gauge, I measure camber, and figure caster from two readings, taken by turning the wheels in/ out. So far as camber, all that amounts to is in/ out tilt and you can at least check the gauge for zero on a plumb surface, and you can check THAT with a level. Rotate the level so the bubble is reversed, and any error should stay on the same end if the level is accurate, IE you put a level on a vertical column, and the bubble, say, "edges" to the post side. of the index mark on the bubble. If you turn the level around, and if it's accurate, the bubble should still be on the "post" side. If it goes outside, the level is "off."