Unfortunately, our yoke was too small. The motor shaft hub did not have clearance to spin freely. A protruding screw head was in the way. See below for the interference.
So, we had to redesign the yoke to increase the size. As we do not have a machine shop to build a proper yoke, we used available parts to expand the size of the yoke to allow the shafts to spin freely and to also securely support the motor. See details below.
We plan on using square tube and hiring a machine shop to cut and drill a better-looking, lighter weight yoke than this one. We want to test the concept at the scrimmage this weekend before we make any final decisions. Below, you can see how the clamp works on a stone in both images and a short video.