Dave, very few companies will stock specialized parts for their older products. I once read that Quad did this for their classic planar speakers, but for the majority of the other manufacturers, it is a non issue. Asides from this, some speaker manufacturers match their drivers to a certain spec that eventhough you might be able to get a replacement, not from the manufacturer, unless you change both the left and the right and someone is willing to match them to close tolerances, your speaker will sound faulty. Are the VMPS speaker drivers sticking out of the cabinets or are they sunk in? If they are sticking out, it should not be too difficult to cut a larger hole with a electric jigsaw...just need to be very careful. If you like the speakers so much, why don't you get a small router set to make the job easier...and you can use it later for other DYI projects.....Another option, check Madisound and tell them the specs of your driver, I am sure they can help you match something close.
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The best customer service I have ever experienced is the Etymotic research people. I bought a pair of E-6 ear isolator earphones, and one of the silicon body molding became frayed, I do not know how. When I called them, they sent me an RA number, I shipped it to them, I got the back the week after. Both of the body molds had been replaced, as well as the ear tips and they ran a full test. All free of charge and out of warranty.
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The best customer service I have ever experienced is the Etymotic research people. I bought a pair of E-6 ear isolator earphones, and one of the silicon body molding became frayed, I do not know how. When I called them, they sent me an RA number, I shipped it to them, I got the back the week after. Both of the body molds had been replaced, as well as the ear tips and they ran a full test. All free of charge and out of warranty.