I've made some improvement by allowing the shank to pivot slightly. I douched the 705 with Neo Lube also.
After watching 705s couple with 714s a bunch of reps I wonder if moving the/a pivot point closer to the coupler is the geometry needed to get more consistent results.
In the past I've cut down brass rectangular tubing to accept N scale coupler boxes for engine pilots. This plow opening is too small for that.