I have an X20 4.5T motor. I have noticed that I can pull the shaft out approx. 1.5mm. I cannot push the shaft in.

It runs fine, though, no problem. Rotates fine, no strange sounds.

But is it OK to have this play in the shaft? Does it need to be shimmed?

Just can't understand how a slop/play can develop if it is shimmed properly from factory?