Thanks for the info on the motor, etc.
If the Explore Scientific OPWB is supposed to be the same as the Gemini G11, then the motor should bolt somehow to the OPWB (or vice-versa) only. The motor and OPWB are supposed to be coupled together as one unit, with the only attachment to the G11 being by the two hex bolts that are currently used to adjust the mesh. This is a good site for some detailed pictures of the setup:
Those 2 existing screw holes in the G11 base plate should not be used with the OPWB as I understand it. If they were used to fasten the motor/OPWB to the G11, then it would render the worm adjustment knob useless/ineffective (because a fine angle adjustment of the mesh would not be possible).
Maybe I should reach out to Scott to see what the plan is for the ES G11?