Let me first thank you all for sharing so much information and assistance. I just acquired a pair of Lancer 77 speakers this weekend. I'm no stranger to small issues like replacing surrounds, and even fixed a shifted magnet on one of my KEF 107 drivers, but these JBLs are puzzling me.symptoms:-some light popping / cracking in the tweeters-if the volume is raised beyond a quiet level, I note that there is mild distortion, and with just a small amount of increased volume drivers seem to be moving in and out uncontrolled at a very high rate. I immediately cut the volume when I saw this happen.i would find it hard to believe that all drivers are bad / blown. How can I tell if this is a crossover problem vs driver issue?i do not know the history of these but would like to resurrect them if possible. If that means replacing drivers I will most likely not invest the $ to fix them thanks all!