esc/motor failure after gentle crash - or defect?

I'm the otherwise happy and newbie quadcopter flier owner of a Cheerson CX-20.

All well and good first day of flying.

The second, a fairly gentle crash that, incidentally, broke one of the landing legs.

Five or six liftoffs after that crash, motor one started stuttering.

Removed the e-clip on the motor shaft, removed the bell. No crud inside.

Cut the heat shrink at the motor wires at the motor - looks like all three wires are still well-attached to the windings.

Checked all the solder points on the ESC - all still round and shiny.

Unplugged and plugged the ESC wires into the FC a couple times.

Still no soap.

Am I overlooking something, or are Cheersons known for having faulty factory-made ESCs or motors?

Stuttering motor is motor 1, for what it's worth. All other motors still work fine.

Thanks in advance.