Gauges on a wipe motor armature stack teeth

[maddenstown]

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Bertie's 1988 MK3 wiper motor became lazy and would not take a load and only rotate with manual assistance. Also gets hot.
This after some months inaction and exposure to the elements, well to put it bluntly, it was the equivalent of his flies being open.
Bertie has retained his composure, and his front chassis is once again fully clad, thanks to Karl.
I started to investigate to-day and discovered three gouges on two of the adjacent stack teeth of the armature and one on a distant one. Do these,like wear on the teeth of a flywheel starter ring in one area, represent slow, fast, and parking settings?
Secondly, are they normal wear? My next thing is to test resistance as per helpful YouTube item re commutator and individual windings; clean commutator (brushes seem fine), then look at gearbox more closely. Any comments most welcome, especially any knowledge of interchangeability with MK 4 or MK5 wiper motors if I find Berties's needs rewinding.

[knobby1]

Those grind marks are for balancing of the armature.

Lord Knobrot