Hi all, I have a pair of the 2-way ESS Monitors with 12" woofer and a 12" passive radiator. found a picture from another thread of the same model I have, for reference below.. The speakers were Mint condition ( all original) when I purchased them from the original owner a few years ago, just beautiful and all most made me shed a tear of appreciation for the opportunity to buy such Minty speakers I had been looking for for several years. Recently, I had the crossovers rebuilt with new caps and resistors, improved the sound to become "tighter", still sounded good as before the recap/rebuild. Questions- at what point do you consider it time for replacing the Heil Diaphragms? Do the Diaphragms degrade over time, or Oxidize in any way? Any measurements test of the diaphragms to do to confirm this? Any way to clean the Diaphragms once removed? for those of you that replaced the diaphragms, was there a noticeable sound improvement swapping the Old to new diaphragms?