Thanks for the support. Every motorcycle I've previously owned had a readily available service manual that explained every detail of the machine. Zero does not have a service manual available, even though the machine is quite simple, and it is left up to us to figure this out and build our own wikipage. Do dealership mechanics have a service manual? I don't believe so. Did they ALL go to Zero mechanic training? We can only hope so, and ask. Until Zero provides a service manual for its customers, the answer to this strange problem is here at electricmotorcycleforum. Thanks everyone.
We will never know the why. Moving on to the what and the how to.
The sprocket/motor shaft spline has a filler goop applied at the factory. It is blue in color, does not melt when heated, and, after the sprocket is off, can be chipped out with a sharp pointed tool. A puller is needed to remove the (original) front sprocket. I believe this is because of the tight tolerance caused by the goop instead of any threadlocking characteristic. When red threadlocker melts it seeps out of the edges as liquid, apparent and obvious. I have chosen to keep the spline clean when reassembling.
Electric travel is power to the people because of the simplicity.
Taking the bitter with the sweet and taking the time to share,
Red Clay