Manually-Operated Manipulators

Problems	Probable Causes	Remedies
A control knob moves too easily, making it difficult to set it to a desired position.	Looseness of the knob.	Adjust the tension of the knob. More details
A set position descends by itself in the Z-axis.	Loose tension of the control knob causing the drive unit to descend by itself.
A control knob moves too easily, causing it to go out of position.	Clearance between the knob and the bearings widened.
A control knob became dislodged.	Looseness of the set screw or excessive rotation of the knob.	Reattach and adjust the knob. Adjust the tension of the knob. More details
Turning the control knob does not allow the drive unit to move.	Find any obstacle getting in the way of the drive unit?	Ensure that no obstacle gets in the way of the drive unit.