Ball lead screw backlash problems

I bought a previously retrofitted BP clone mill and I'm just getting
it up an running with a new PC based control.

I'm seeing more backlash on the X and Y lead screws than there should
be- .001" on the X and 0.004" on the Y.

The backlash is uniform on the full length of both screws, so it looks
like the nuts are worn but not the screw themselves. So far I can't
find any manufacturers names on the screws, and I can't see the nuts
very well without taking the table off.

Is it possible to replace just the nut on a ball lead screw or will I
have to replace the whole set to get rid of this backlash?

Thanks,

Paul T.