jonny didmo;

First, a broken propeller should never be repaired. There is to little surface and to many rpms. If it lets go, and it probably will, you could lose an eye. $2.00 for another prop is way cheaper than an eye.
The capacitors reduce electrical interference to the Rx from the arcing of the brushes or comm arms. They do nothing else. And the N20's will probably kill the AA Rx outputs. They draw more current than a standard AA motor. If you have a meter to measure the current of the N20 w/prop it would let you know for sure. A standard AA motor draws 380ma with the prop at full throttle.
The mod that was referred to previously will let you use motors that will draw 4.3A per side. So motor size isn't really an issue if they are installed.
We have the parts in stock if you can solder something that small or we can do it for you.

Tony
ARS Software & Innovative Solutions
http://www.falcon1.net/ars~/rcmodels.html