I have just taken the stacked knobs off my ACG (they needed a clean) and I've discovered that a couple of them (two out of three of the stacked knobs) had springs between the upper and lower knob, the remaining stacked know had no spring. Are these springs usually to be found between the knobs like this, I suppose I should ask @skelf really. Having done the same previously with the Harlot it had no springs in the stacked knobs.