My suspicion is that a glitch buster is not going to help in this scenario. A glitch buster supplements a voltage sag coming from the BEC when running the servo directly off of the receiver, since you are connected directly to the battery I do not believe this is the scenario here. You can also try running the ground wire back to the receiver and only running the power wire to the battery to see if it makes a difference. Again I'm speculating here, but generally a capacitor helps with a "brown-out" which is caused by a momentary loss of power, it doesn't sound like that is what is causing you issue. The symptom of a brown out is usually a loss of control.