german patent no 3 712 673 the armature face 4 is provided on the shank 1 at the narrow side underside 5 which is opposite from the ejector butt 2 and the control butt 3 in the region of the narrow side 5 a narrow elongated control spring 6 is provided which projects from the shank 1 and which is an integral part thereof the thickness of the control spring 6 measured in a direction perpendicular to the plane of the drawing figure accordingly corresponds to the thickness of the shank 1 stamped of sheet metal and further the control spring 6 lies in the plane of the shank 1 in individual cases taking into consideration the spring characteristics of the control spring to be obtained or for other reasons it may be expedient to reduce the thickness of the control spring 6 relative to that of the shank 1 such a reduction may be effected for example by a pressing or grinding step subsequent to the stamping process the control spring 6 has a free end portion 7 which is bent slightly in a spoon like manner and an opposite end portion 8 by means of which the control spring 6 is formed on the shank 1 as shown in the figure the control spring 6 is slightly tapering from the end portion 8 toward the free end portion 7 and has a slightly concave configuration as viewed from below between the control spring 6 and the facing narrow side 9 of the shank 1 an edgewise open recess or bay 10 is provided in the shank 1 the bay 10 forms a space which is open at the free end 7 of the control spring 6 in.