I just picked up a free Rich Bit Top-012 ebike. My friend used it for a couple of weeks but thinks he burnt out the motor by overworking it (he was using it to tow a large trailer at parties). He bought himself a new bike and then put this one into the shed and forgot about it. The bike is in amazing condition except for the motor which works intermittently.

I've searched but can't find any parts specific to this bike, (300w 36v) as the Rich Bit site themselves only show parts for the 48V version.

Do you think it's possible to either

a) find a replacement 36v motor (a search reveals lots of 36v motors, I just don't know how swappable they are)
b) replace the motor, controller and battery with the new 48v versions?