I'm seeing several places that are now shipping undersized rubbers with their kits. When dealing with one, I often use a drill to enlarge the hole pattern a bit before I start.
With three hole backing plates, I put in all 9 bolts loosely, then begin to tighten the three in the centers of the plates - this is when I tap the sprocket into line for as the up/down alignment and not worrying yet about the left/right wobble.
Then, I tighten all bolts fairly tight and see what I've got - followed by tightening more as needed to pull it in for left/right.
With practice, it goes pretty quickly.
With three hole backing plates, I put in all 9 bolts loosely, then begin to tighten the three in the centers of the plates - this is when I tap the sprocket into line for as the up/down alignment and not worrying yet about the left/right wobble.
Then, I tighten all bolts fairly tight and see what I've got - followed by tightening more as needed to pull it in for left/right.
With practice, it goes pretty quickly.
