I've had TMCC knobs that had alot of resistance, others were very loose out of the package. No rhyme or reason, but its a good thing Lionel added detents to the knob rotation of the Legacy handheld.
When it gets really interesting is when the rheostat of the knob fails completely and trains take off at full speed. If your lucky..... after a few rotations of the knob, "zero" will reappear. I've had bad ones out of the package as well.