I have been collecting and refurbishing speakers for the past ten years or so, mostly AR, KLH, Advent, etc. I just came upon a pair of 7B's, they are my first Polk speakers. One of the speakers works well, while the other does not put out any sound. After opening it up, I was immediately stuck as the crossover is quite different then any that I have ever worked on. Could someone help me with getting into the crossover? It appears that there are a couple of circular boards that are snapped together, do I just pull up on the upper board until it snaps free? I just want to make sure that I don't cause any damage to it while trying to get at it.