Mokshaq

I have a pair of Tangent 500's, and one of the woofers may be in need of replacement. My son dented the dust cap a number of years ago, and now when I play certain levels of bass, there is a rattling sound emminating from that speaker. An audiophile friend of mine, suggested that perhaps the coil behind the dustcap was in some way damaged, and that I would need to replace both woofers to keep the sound consistent from one speaker to another. Any suggestions? Also, I have seen posted that the cabinets for the Tangents are not big enough. I work at a Abrasive WaterJet cutting facility, and can easily cut and replace the cabinets, does anyone have any good info on what kind of design would be optimal? Thanks much, Ya'll Rock the house...