I'll just chuck the key up into the vise, and grind it down to the right size. Then test fit it into the groove.
Next I want to make an 0.125 inch groove in the shaft. The problem I have is how to hold the shaft. I need to clamp the shaft to the table before I can machine it. It would be nice to have a set of V Blocks to do this, but I don't. So, gotta make something similar. I have some Steel bar stock that I can use to make a U Block.
Next I need to re-install the magnets on the Rotor and get back to testing.