iOptron CEM40 Instruction Manual page 48

2. Spring plunger position related to meshing result
The gear switch should be adjusted to a position that between 2 and 4.
3. Gear Switch Meshing Adjustment
To Adjust DEC Gear:
Disengage DEC gear switch
0
Disengaged position
1
Not touched. There will be free play
2
Just touched. Minimum meshing force. No free play
Engaged position. Normal operation position
3
Plunger adjusted too much. Ball had been pushed
4
all the way in and no spring loading power
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