This paper outlines the problem, and describes the solution, of developing a means of measuring the beam position of captive production illuminators to allow their use as tooling alignment light sources. The Xerox 9700 Laser Printer, which has a throughput of 120 pages per minute, uses a 25mw argon ion laser as its light source. The laser printer optical assembly is split into two units. 1. The illuminator consists of the laser, beam conditioning optics, modulator, and beam pointing mirrors. This unit is removable from the second half, and is field replaceable. 2. The scanning laser output terminal (SLOT) consisting of the motor polygon assembly, scanning optics, mirrors, scan line detectors, and exit window is a permanently attached assembly to the printing engine frame. The illuminator and slot assemblies are manufactured in two different locations, and the slot is optically aligned utilizing a captive illuminator as a tooling light source. The beam pointing tolerances of the captive tooling illuminators are set to tighter limits than normal production units. In order to align the beam exiting the illuminator, a tool was designed and built which is self-calibrating and has been demonstrated to measure the beam position to an accuracy of 0.0001 an inch, which is sufficient to allow adjustment and verification of the tooling illuminators, reference Figures 1 and 2.