Loosen the clamp screw(s) and move slightly toward the helix if gage is reading high. and away if reading low.
Azimuth must be set with clamp screwed down because of angle in platter surface.
When inserting the needle into the clamp, push it up as far as it will go and tighten the clamp screw firmly with the screwdriver.
To renew a broken clamp screw for air port in fitter's quarter.