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Dismount the Y axis motor by backing out the four SHCS holding the motor to the casting, and pull it out of the way - be careful not to stress the motor wire leads. It should slide off the ball screw.
The ball screw and ball nut Ball Screw and Ball Nut are now free to be removed. Make sure the Ball Nut oil line is not obstructing the Ball Nut itself. Slide the ball screw assembly out the back of the machine.
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Install replacement Ball Screw
To install the new ball screwBall Screw, simply follow the steps above in reverse. Then, reference the Lost Motion and ACB/Gib adjustment document. Make sure the oil is back in place to properly lubricate the Ball Nut.