I am not sure if I am following you 100%, but it sounds lie you have the same problem which is the frozen detent that rests against that notched bar. I am going to use penetrant and heat daily and hope it eventually budges but so far..nothing.
Joe, in most of my machines I prefer to clean them up a bit to know they are running at peak performance and I am weird that way. I find they smell less like old trains when the old carbon dust is cleaned out and I like a clean commutator. In this case I am likely to do as you say and not go poking around where it's not really needed.