GEAR SETTING

[cutter]

The exact center distance between the two helical gears
   for the RGG design is .625.
   Because backlash is not important it’s better to favor the + side.
   Also consider the run-out.
   If one gear runs out a total of .002 then add .001 and the other
   A total of .004 add .002.

   .625 + .001 + .002 + a couple for backlash .002 = .630

   Formula from The Machinist Hand Book

I was sure it was a particular bolt hanging up \'every other turn\' of the crank. But no. Binding like that is in the helicals, which were too close to each other.