what i ended up replacing was the double bearing set for the preload on the y-axis $40 for the set tormach # 30430 and the complete y-axis ball screw with nut $525 tormach # 30448. you can not just purchase the ball screw nut but you have to get the complete matched unit. the oil line can be attached from the top just under the back bellow.
blessings!
craig