1. Make sure the head is level.
2. Adjust the slide parallel to the back of the camera using visual inspection. The center of the lens needs to be in the center of the panning tool. View the lens from the front with a vertical level. Move the side to side slider until the center of the lens, with the center of the track, and the edge of the vertical level all align,  
3. Next adjust the slide perpendicular to the camera back. 
4. Place a couple of test targets in front of the lens. Place one target very near and the other about a meter farther away. The rear target is a little higher up in order to see both in the viewfinder.  Initially, the test targets should line up perfectly while your camera is pointed straight ahead.
5. Loosen the lock on the panning clamp and swing the rig left and right noting the alignment of the targets. Adjust the slide forwards and backwards with trial and error to eliminate parallax by experimentation.
6. Record your results so that your setup can be re-created.

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