The rod will spin with both of the lock nuts loose, this is normal.
Like Miller said, just hold the rod with pliers and turn the lock nuts to get the WG set correctly.
Here is the Post I did from a few years ago when I got the official WG reset procedure from a GM Tech:
"The instructions posted to the Techs are:
1. Loosen counter set locking nut and spin out of the way to the right.
2. Back off the left nut until no pressure is felt on the rod from the diaphragm.
3. Now spin the left nut back to the right until you just feel the spring pressure from the diaphragm and stop.
4. Now turn the left nut 2 (or 3, can't remember) more complete revolutions.
5. Lastly, spin counter set locking nut on the right, back towards the adjustment and set tight.
6. Be sure to use lock tight on both nuts. "
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