A readwrite head servo control system for data recording devices, wherein a method of compensating initial values is utilized to generate a control signal to move the head from an initial position to a target position. In one form, the \u201cballs\u201d are fit into voids drilled or otherwise provided in a portion of the pen cap and press fit, or otherwise attached, thereto. The first polyether has an acid number of at least 8, preferably at least 12, and the second polyether has 30-70 wt % of lipophilic parts. Using the estimated fringe spacings, four phase-shifted fringe patterns are generated by correlation integration and then used in a phase calculation to obtain wrapped phase information for the object. With this arrangement, the electrical connector enables a stable inspection for integrated circuit pads in a manner which minimizes irregularities in repeatedly measured values of electric resistance and skew.