overlying relation to bracket 60 the tip or distal end of contact arm 62 comprises an electric contact 70 that can be either an integral formation in the arm such as a dimple one or more tines or fingers or a separate contact element that is affixed to the arm by any suitable process fig7 shows that rear housing wall 32 comprises an embossment 72 at its center embossment 72 is created during the drawing of the cup that forms housing 30 embossment 72 is shaped to provide a circular depression or pocket 74 on the interior of enclosure 31 and a circular riser 76 on the exterior pocket 74 accurately and sturdily seats a circular head 78 of a post 80 so that the post extends within the enclosure along a central main axis 81 that is perpendicular to wall 32 and parallel to and concentric with perimeter wall portions 38 40 embossment 72 may be formed in a way that allows post 80 to be assembled to housing 30 by pressing head 78 into pocket 74 additional means of attachment such as welding or the like may be used as appropriate as can be appreciated from consideration of fig7 movement 52 is associated with housing 30 prior to placement of cover 28 with post 80 having been assembled to the housing movement 52 is placed on post 80 by aligning eyelet 64 with the post and moving the two toward each other contact arm 62 has an aperture 83 fig4 that allows post 80 to pass through without interference the.