striderjg, I had considered your method but rejected it on the grounds that it is harder to accurately gauge how deep your cut is until you see sparks flying, then it is too late as you have started cutting the shaft thread. By using the hacksaw method , if you inadvertantly go a fraction too deep, the hard steel of the thread will soon let you know you are deep enough , so stop immediately. In preferrence i would use a junior hacksaw, as the teeth are finer to start with and as the motor is still atached to the aircraft, it will be easier to control.
tramsay, i would refrain from using heat at all , as it is difficult to control the amount of heat you will require, so consequently you could run the risk of damage to the front bearing.
I hope this has been of assistance to you and you have success in fixing your problem. I also apologise for the spelling mistakes in my previous posts.
Bill