revive old ball screw stage

I have a XY stage with 4" travel purchased from ebay about 10 years ago and shelved since then.  It was probably old then, it has the round stepper motors but no manufacturer information or date.  No matter, I plan to put new steppers on it and put it into service under my surface grinder.

It has 5 tpi ball screws and roller bearings guides, ball bearing thrust bearings.

Here's the problem: the screws are very stiff.  I've been spraying WD40 on them and turning them back and forth with an electric drill, but this seems to only made them slightly looser.

The stiffness seems constant throughout the travel.  There is no noticeable backlash.

Taking the whole thing apart can be done, but then I'd just have a pile of unaligned parts which would be a pita to reassemble properly.

Any ideas?

This will be put under control of Mach3 and my Xylotex box when it's runs well enough.

Elliot