Some side to side shaft play is normal. Depending on how hard you push. It's the in and out shaft play you need to worry about. My freshly rebuilt turbos did about the same thing. I've got over 1000 miles on them now and they're still strong. I used G-pop shop for the rebuild and I'm sure they can explain it better if you call them. Nice guys. I was extremely worried when I got them back. talk to some guys that actually rebuild and balance turbos they should be able to give you more insight.