You have quite a project ahead of you. For me, I'd loosen both collets on the motor drive shaft. I've found it easier to move the slide if both collets are loose. You'll need a 1 1/2" crows foot, appropriate sized ratchet and a cheater bar (4' should do it). I use a 6' cheater, but that is because I weigh only 158 lbs and have no upper body strength. Only loosen the collets. These are collets not collars. They are on a taper. Even with the collets loosen, you'll need some friends to help. This slide is heavy. Best I remember it is a right hand thread. Do not use an open end or adjustable wrench. One can not get the extension leverage needed. It is easy to hurt yourself messing with these collets.
Once the nuts are loose, consider moving the slide mechanism just a bit to break the taper from the shaft.
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