Andrew,
I appreciate your comments.....but....
The way the 'motor' is assembled is like this:
Take the field coil assembly, insert from the front, the armature, carrying its front bearing and support bracket. Add from the rear, the rear bearing support bracket c/w brush box assembly. Now, from the front support bracket add the through bolts to clamp the assembly together. Add the brushes to the holders.
Job done....
The rear bearing housing is bolted on from the front so it cant be removed......
So, basically the fan has to be removed first, the front bearing housing is fastened to the drill casing from the front too, the securing screws are behind the fan, once removed, the whole motor assemble emerges from the back of the drill housing......You can see the mounting lugs in the body around 7:13 in the video....
His strip down was made easier because his fan had broken in two...