if the ballnut " gravity spins " the whole way its thrashed. It should have tension, about 5 lbs or so ona fish scale when turning slowly in a lathe IIRC. to check ballnut lash, fix a magbase on the sliding component to the " side of the groove of the screw. Theoretically the lead of the screw should be constant poisition, move the slide back and forth and/ or pry to overcome gravity while observing the indicator. To check the spindle insert a long tool/ test bar, 6" is my recomended min tool length. Psh by hand on the spindle, observing the indicator. This can be spindle bearings, drawbar springs, but if it moves noticably she may have an issue. If the rails are " pitted " where the balls ride they are thrashed, but some texture is liveable depending on tolerances. I don't have any transmission machines.... If you want to see what she does put her under power and cut it as is. From your first post I assumed it was a machine you'd had a while.