I'm going to guess you're buying a lathe of Asian origin. Very common to
have issues like this. get as much as you can out of the vendor.

From there, many consider these lathes "a work in progress". You'll need to
modify it for nice performance. I've seen threads on this NG, at CNCzone.com
and especially in Home Shop Machinist magazine. There's an index of back
issue articles on their website.

Karl