Ensure the three spring-loaded pins that mark the lens are properly aligned and not bent. If a pin is bent, carefully straighten it using pliers.
The marker lever controls the position of the pins. If the pins are not marking the lens at the correct location, adjust the marker lever. Loosen the set screw, move the lever to the desired position, and retighten the screw.
The lens stop is the surface where the lens rests. It must be perpendicular to the optical axis. If it is misaligned, loosen the screws holding the stop and adjust its position. Tighten the screws when the stop is at a 90° angle to the axis.
The gimbal is the swiveling arm that holds the lens. Ensure it rotates smoothly and the lens remains centered when moved. If the gimbal is loose, tighten the pivot screws. If it is too tight, loosen the screws slightly.
With no lens in place, the axis lines in the eyepiece should cross at the exact center. If they are misaligned, use the axis adjustment wheel to center them. Refer to the manufacturer's instructions for the proper calibration procedure.
After making adjustments, check the alignment using a known good lens. The pins should mark the optical center accurately. If not, repeat the adjustment process.
Before you attempt any repairs check the warranty. Often any attempts made by unauthorised technicians will void the warranty. If the pin misalignment persists or you are uncomfortable making the adjustments, it is best to have the lensometer serviced by a qualified technician. Improper repairs can lead to inaccurate measurements.