The function isn't altered. The function of the weighted servos are to give the rumble feedback when gaming with the controller.
The original parts are still the original parts, just in different controllers. I took one original part out of one controller, plugged it into another controller I want to use, then close it up and play.
alteration - an event that occurs when something passes from one state or phase to another; "the change was intended to increase sales"; "this storm is certainly a change for the worse"; "the neighborhood had undergone few modifications since his last visit years ago"
The controller is still a controller when I move a heavy weighted servo into the slot of a small weight servo. It rumbles MORE to my preference. Still a customization not a modification. The function is still to rumble. If it were a modification I'd have altered the function of the servo and made the tiny motor play showtunes while I get shot or blow up from a grenade.
The servo has not been modified or altered as it moves from ONE controller to ANOTHER. Neither has the slot it's being placed into. The controller gave rumble feedback before, now it gives more rumble feedback but still rumbles and still gives in-game feedback.
Also, a modification would also be if a game developer altered the function of rumble feedback and had it so during the cutscenes of the single player, your controller gave constant rumble feedback, but during the game, gave no feedback at all when you were shot or blow up by a grenade or having a bumpy ride in a vehicle.
Again, I do not mod. Here is my BIO: