the feathering spindle CAN be centered,i have done it as described.if the dampers stick out furthar on one side then assuming all spacers are the same,which they are, if you put the blade grip on to that side and tighten all the nut's then measure,you will see that the blade grip on the side where the damper sticks out,is furthar from the centre of the head than the other blade grip,causing a vibration in the head.think about it,the spindle does not centre it'self,it simply has an equal amount atatched to both ends of it.that way it cannot move either left or right when tightened because the spacers will stop it.if you want to see this for yourself then remove one of the spacers on your heli and replace it with a slightly larger one,then reassemble it and fly it,you will now find that the heli has an annoying vibration in the tail and if you measure the blade grip distance,you will see that one grip is slightly furthar away from the centre than the other.this procedure is outlined also in rays helicopter manual