[Herald1360]

I'd be inclined to pull the coil (series choke) apart and attempt to rewind it. Once you've found out roughly what gauge wire was used, a simple fill the space winding should work OK. If it's just in series with the mains to the motor and the winding can take the current, there's little chance of any problem if it's not quite right. If the fan's too slow, just remove turns......

You might get away with a suitable capacitor but be very wary of any resonance at 50Hz if you try it.