turbo shaft play testing checking

I sold this used turbocharger to a guy he received it and was very unhappy and said that it has end to end play and .050 sided to side play. Well I have another one here just like it I spin it I pull I try and move it side to side I get a little end to end play. I then bang it on the table (dropped it) then sure enough there’s side to side play about .050. Any one have a better guess than banging it loosened up some coking on the bearings that. was not so bad as to interfere with hand spin test. But the worn bearing was being shimmed by the burnt oil residue. Or is it a case whenever you bang the unit the rotating shaft can slide off the bearing surface and the unit are fine when you spool it up it will ride right back to its proper running position with no side to side movement. When checking for play how hard should you pull out push in? How hard should you push sideways or pull side ways on the impeller?
Thanks for any help
Dave S