Before jogging the Z-Axis in recovery, the machine wants the drawbar to be unclamped. Then you can jog Z-Axis using the commands in recovery; it moves very slow though. When pressing unclamp in recovery, the drawbar will unclamp and stay open until you press the button again.

If the spindle is empty, try the following steps instead of using recovery.
Press the ZERO or ZERO RTN button just above LIST PGM button
then press SINGLE AXIS which is to the right of the ZERO button.

Usually this results in the shuttle returning to its home position.
If that does not work, you can manually push the shuttle to the home position.
When looking from the top of the shuttle casting, you should see a steel arm that drives the shuttle forward and reverse; it is the same bar that activates the switches. Push that bar down a little, then you should be able to push the whole shuttle assembly back to its home position. You may need to help the bar reach its horizontal position to activate the shuttle out switch.

Good luck!