[OCCRA]: motor brush springs

[greencactus3]

new drill motor brush springs. after soldering the wires to the motor, and testing, i noticed it did not work.. why? because the brush spring had popped off and the brush was not pressed against the comm.
it was quite difficult to place the spring back because of the lack of "finger-space" is there an easy way to remove the endbell of the motor other than bending the part of the bell back? it would make access easier... the reason i want to have more access is, with rc car experience, i know stiffer brush springs will give more low end torque to the motor and softer springs will allow more higher rpms. will it be a bad idea to turn the brush springs, which are coiled, and extra 90 or 180 degrees (=stiffer springs)?
this kind of spring definitly seems easily adjustable without having to buy new ones. does this count as modification to the motor?