Elcometer 121/2 Operating Instructions Manual page 8

3.2 CHANGING TOOLS
When changing from one cutter to another, first press the 'Stop' knob against the casing. Then turn the
rotary head to the desired position and lock it by releasing the 'Stop' knob.
Note: Care must be taken that the 'Stop' knob distinctly and audibly snaps into place.
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