They are durabond bearings. Attached is a picture, they all have contact wear at the bottom, some more some less. until I measure the bore I don't know how much the wear is, probably .001-.002 or so. So how much is too much ???? I haven't looked it up, but around .002 total clearance sounds about right. The issue may also be straightness of the bore....

I looked at a couple of blocks I have, they all have wear at the bottom of the bearings, which makes sense to me as all of the springs are putting force in that direction.