I hope you mean hub and not rotor, or this would introduce another unnecessary variable. The rotor should be off for this procedure.

I don't see how rotation could be a problem. Once it's set up as previously described, you simply grab the hub and push-pull to get a reading. Magnetic base is on the hub.... dial indicator is on the spindle end, measuring in the axial direction. Are you sure you're wiggling correctly? Wiggling should be in the axial direction, not radial.

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95 E320 Cabriolet, 169K