[neallewis]

I wouldn't run it just yet.

If you have a decent multimeter, measure the resistance of each coil, from B to A and C, From A to B and C, and from C to A and and B. Note down all values. They should all be very close to identical.

You can also spin the rotor with a battery drill and measure the AC voltage induced on each coil. It should be the same on each phase.

If any coil readings are different I'd suspect the odd phase has burned/shorted out.

A sensor board could have gone (and been replaced), but I wouldn't have thought it would have burned up enough to cause such a smell. The hall sensors in the board are very low current devices, and basically react to the changing magnetic field to feedback the motors rotor position to the speed controller. The smell must be from the stator (coils).