My father-in law's 075 tweeters need the diaphragms replaced. I contacted JBL and was told that he could use the 2405 diaphragm if the phase plug was milled down to create the proper air gap. My question is what is the proper air gap? And where can I have these phase plugs sent to be milled to the proper size? Or can they be replaced by another properly sized phase plug? JBL wont help with this repair nor would they recommend anyone to help us. Any idea's forum members?