Well, I don't know if you can apply logic to this but on the parts diagram the set screw for the motor pulley uses a 3mm wrench. So does the center....
What size is the setscrew for the stock Grizzly G0766 Live center to hold the point? I remove the center point when turning bespoke fountain pens to...
On my former G0698 18/47 The belt had a little bump of rubber build up on the ribs where they spliced the ends together. Not really noticeable until...