[glennpm]

I think you should look at the run-out of the pulley, i.e the amount between minimum and maximum at a point on the pulley.


I'd pull the plugs and try to get a helper; or turn crank bolt manually as you watch; or make a starter switch to bump it (ignition off).


If this static view isn't conclusive, I'd run it motor running through different RPMs with a helper and watch to see if you have dynamics of the pulley and/or crank snout vibrating from bending forces.