OK, I just thought I might have been missing something - Olsen's didn't have it and neither did Greenberg, so that was my first clue(s)
I'm mostly through repairing/cleaning it, but wanted to be certain I was stacking washers in the right order on both the armature and the coupler centering assembly. This one suffered greatly from over-zealous oiling (esp the commutator) and what I guess must have been a "ooops, I dropped it" or a "step-on" moment to have put the very slight bend in the axle, but it sure caused some binding - fixed now!
Thanks for the feedback!
George