After some cursing I tested the fitting. Thankfully everything worked as needed. Also discussed what's coming up next and in particular the fitting of a nylon replacement cog inside the motor because it makes the motor run quieter and it is reputedly stronger than the cog shipped with the Bafang motor. Before I do anything like this I always try to read up on what if any are the possible failure modes associated with equipment I am about to buy. This practice stems from owing motor bikes over the years and trying to steer myself clear of incurring unnecessary costs down the road.