I'm afraid that's still nebulous. The bearing blocks always have a little wiggle in them in their frame slots. Deciding how much is "wrong" is not easy to judge from here.
If it's play in the bearings you want to get rid of, about all you can do is put tiny shims in there between the bearing and the side of the slot. I have done this (not on a Kato/Con-Cor Hudson, but on other engines) with very thin (like .002" brass) shim stock.
You cut a little rectangle of brass out with a sharp Xacto, and then wrap it around the edge of the bearing slot (picture the little brass bit bending in a "U" right around the edge of the slot). Then put the axle/bearings back in. It doesn't take much to keep those bearings from moving, so start thin and see how it goes. They MUST have a little play so that they can adjust to track variations. I would also suggest shimming on only one side of each slot, and doing them all on the same side. For example, wrap a .002" shim around the back edge of each slot. That way all the axles are nudged forward by your shims.
