Years ago my brother-in-law bought the old balancer from the Buick dealereship, the tech said he hated to see it go. it did a better job than the new ones but took about 15 minutes per tire and they lost money using it. He said they would use it when they had a problem getting a smoth ride with the new one.. I now have it . you first do a static balance in the on car position then unlock the spindle and rotate it 90 ' and spin it with a drive motor. It has a spring loaded disc that you lift the handle to contact the disc to make it run true while the tire wobbles. then unlock the spindle and rotate it back to the on car position, flip the indicatator into position and rotate the wheel by hand and the indicator shows how much weight to add and to the inside or outside of the rim. take enough time and it does a good job.