iOptron CEM40 Instruction Manual page 49

Rotate DEC saddle to exposure the small hole (3mm in diameter) that is blocked by the dovetail saddle.
Another larger hole (5mm) is located on the side of the DEC gear housing. There is a set screw inside
the 3mm hole which locks the gear meshing adjustment screw, which is inside the larger hole.
Engage the worm/gear by turn the gear switch to locking position.
Insert the 2mm hex key into the small hole on the top. Gently turn the hex key until you feel it is
engaged to the set screw inside. You may turn the gear switch further in the lock position if the wrench
can't engage the set screw. Turn the set screw half a turn counterclockwise to release it.
Adjust the gear adjustment screw on the side inside the large hole by using the 3mm hex key. Turn
counterclockwise to loosen the meshing or turn clockwise to tighten the meshing.
If the motor stalls or the mount does not tracking smoothly, most likely the meshing is too tight. You
may loosen it by about 1/8 turn (or less for tracking). Tighten the set screw in the small hole to
LOCK the gear screw (important) before test the mount. Adjust again if needed, but no more than
¼ turn in total.
3mm
5mm
49