I was just thinking - make sure they make a good square contact with the hub - but do jack the car up & wrestle the wheel to see if it moves at all (might be worth axle stands if you're feeling too strong!)
could be something as weird as a loose ball joint or something (but as you're proving, very hard to find)
could be something as weird as a loose ball joint or something (but as you're proving, very hard to find)