If you have an excess of roughly 0.002 run-out, see if you can loosen the attaching nut if this is the case here. Loosen the nut holding the unit on, then try rotating the unit 180 degrees and repeatedly shifting the part. If run-out decreases with movement in one direction you are on the right track, but if it increases when retorqueing you are positioning it in the wrong direction.

Try increments of 90 degrees if this is to much. Check the manufacturers specs to see what is tolerable in run-out specs. The unit will settle into another position (centering) as you move it basically. The unit will reposition itself even on a tapered collar..or actually you are centering it basically to reduce run-out.
I like to stay close as within 0.002...some condider this very close to safe run-out--check manuf. tolerances..