Rich, from my Navy Aircraft Mech days, Dzus buttons come in different lengths. Not sure if they are in 1/16" increments or finer, but your "teak the spring" method works for small adjustments for sure. They have a super thin conical washer that fits over the button shank, after it's in the panel to be retained, and then is deformed to keep the buttons in place when the panel is loose. Lot's handier than having the buttons loose and scattered around, especially if you have different length buttons for the different panel thicknesses.