Just a thought but assume that there is no play in the bearing???
Have you got anything stuck between the hub and disc to put it out of alignment??
As Steve said above check if hub is ok
Easy way to get an idea is with a couple of bits of wood and a nail.
Just place the nail head against the disc and turn the disc slowly round
Check the centre as well
Plus if you remove the disc you can check it against the hub as Steve suggested
Just put the nail head against the hub face on the outside of the bolt holes. (Ie close to the edge as possible)
( by the way, this is an old picture ...I didnt strip it all down just to take a picture of it for you

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