Why don't you place the + & - leads to the motor inputs and see what will happen.
12v from a battery directly to motor plug contacts, if motor goes in wrong direction reverse the wires to the motor contacts.
A 12v battery not from control board as someone asked.
You may also have a poor ground someplace suppling the control board and that could be from your master 12v fuse panel both + & - screws could be loose.
If motor still does not move check
out this link for motor also.
This may not be your
slide control but will give some info on slide operation.
You may have this
slide control, these controls have P numbers of MFG you maybe able to find on web.