Rule of thumb on both sprockets and pulleys, if it wobbles it's wrong & not only bearings suffer but also belt or chain wear results as well. Any part of any drive train that doesn't run true is a problem and that includes wheel axles and Jack shafts that are mis-aligned and cause belts or chains to run tight and loose on each 360 degree rotation. The quick check for this is rotate the rear wheel with one hand slowly while feeling the tension on the belt or chain with the other, one rotation of the wheel will tell you if the axle/shaft alignment is true. If at points the belt/chain is tight but looses noticeably at other points during rotation there's a problem, typically it's the rear axle installed crooked, or a bent axle etc. CVT belt is similar in principle but because of the way it's designed trouble shooting the problem of concentricity is a little different in execution, compared to that used on of the rear section of the drive train. I would use a dial gauge to test the pulley by rotating the pulley while touching the pulley surface close to the outer edge with my hand supported on a steady rest. This can work ok as well. Rick C.