Sokkia im-101 Operator's Manual page 217

3. Turn the upper part through 180° and check the bubble position.
If the bubble is still centered, no adjustment is necessary.
If the bubble is off-center, adjust as follows.
4. Correct half of the bubble displacement using levelling foot screw C.
5. Correct the remaining half of the displacement by using the
adjustment pin to rotate the plate level adjustment screw.
When the plate level adjustment screw is turned in the
counterclockwise direction, the bubble moves in the same direction.
6. Rotate the top of the instrument and continue adjustments until the
bubble remains centered for any position of the upper part.
If the bubble does not move to the center even when the adjustment
has been repeated, ask your local dealer to adjust it.
• Adjust the optical plummet of the AP41 instrument height adaptor
following the checking and adjustment methods of optical plummet.

"35.5 Optical Plummet"
Base Plate (TR-101/102/103R series)

The circular level on the base plate for prism should be adjusted in the
same way with the circular level on the main body.

"35.1 Circular Level"
211
38. TARGET SYSTEM