Abstract: In order that lowering of the transfer tube of the head may take place properly, motors and linkages enter into action. A particular arrangement of a pivot of one lever, comprising a notch on the pivot and an aperture in a bearing piece, brings about a compulsory first phase of lowering and a containable end of lowering. The proper adjustments are simpler, annoyances due to inertia are eliminated. An automatic arrangement allows the release force to be regulated. Centering jaws are actuated radially by a similar motor-operated control arrangement. The machine is especially suitable for producing electronic circuits.