Sand it flat, and after that have a look at the brush holder.? Looks like the brush is going in at an angle which is why the brush tip is angled when it should have a curve in it.
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Holder might have come loose or cracked.? You see this sometimes when a motor gets hot and the holder melts.? The bit the brush goes in is metal, but it’ll be attached to a plastic base (used to bakelite in the olden days).