My what a wonderful job of documentation!
A couple of thoughts, re:
1) On pulling the armature out and re-inserting it: I have used a car floor jack to separate or re-unite them under control. As you correctly point out several times, the forces are immense!
2) On page 42, the mis-alignment can be dealt with by scratching "truth marks" across the cover and case before separating them. There's no sense in hoping that a Chinese factory will drill all eight screws in a perfect distribution around the circle. By re-aligning the "truth marks" you ensure that the SAME holes and threads are aligned.
3) I wonder if it would be possible to substitute an external relay for the internal "shift mechanism" that switches the coil arrangement for low and high "gear."
4) Judging by the apparent ease that the motor can overheat, I wonder if there is any way to get a thermistor in there to keep it from happening. Re-winding that sucker is not something I'd hope to have to do!