Join Date: Apr 2012
Location: Greater Vancouver
Yes, some folks have had issues with the "old" Scootworks front pulley. I have not heard of any issues with the rear.
I suppose I am a bit biased, but having the BARON'S rear pulley on the bike (with a taller rear tire, in my case) makes such a huge difference that I would never go back to the stock rear pulley (note to dirtwiz).
A very slight machining error would not likely show up using a block of wood and a calliper. You would have to do a "runout" test on the pulley itself with a proper runout dial indicator, preferably in a lathe, correctly mounted. It does seem a bit hard to believe that the Scootworks factory machined the piece with a wobble, but stranger things have happened.
As Bosco said, he had a very small (but visible) wobble, but it worked itself out in the first few hundred miles of riding. I would re-torque the mounting nuts after those few hundred miles, you can do this right on the bike no problem.
Give it another go before trying to return the part.
BTW, I would be more worried about incorrectly mounting the front pulley as you cannot see it on a daily basis, and it also must be carefully mounted and torqued exactly to spec.