mounted on a horizontal shaft 85 and turned by a step motor 86 also mounted on the bracket 81 the cam wheel moves between two rotatable cam followers 87 mounted on the lower ends of members 76 and 77 a portion of the cam wheel 84a is wide enough to force the lower ends of the members 76 and 77 apart sufficiently to produce a pinching action on the transistor leads when the thin portion 84b of the cam wheel is between the cam followers 87 a helical spring 88 pulls the lower ends of members 76 and 77 together and separates the upper ends so that the transistor leads 27a are free to be moved to a new position by wheel 32 it should be noted that a small resilient action is available in back up insulator 76 since it is thin enough to be bent a small amount when the upper ends of the members 76 77 are moved together also contact terminals 30 are resilient and produce a small wiping action on contact sufficient to remove any dirt from the transistor leads 27a as contact is made in order to produce a fast acting machine the testing wheel 32 is made of light weight material and is supported at its periphery by two air bearings 90 positioned adjacent to the underside of the wheel and supported by base members 90a the base members include valves a.