Ebay should step up since it is an item purchased through its service. At the very least, you can bring a complaint against this seller, which will immediately affect the seller's approval rating.
The safest choice is to send them to Grado in America and pay whatever Grado charges. The stories of Grado's outstanding customer service are as common as those complaining of Grado's "workmanship," mostly discontent with surface scratches, splotchy gluing and gimbals becoming loose or disconnected. Hand-made headphones often come with little imperfections but none have ever affected my enjoyment of new Grado cans.
Reading what little you wrote about the problem, I'm skeptical that there's anything fundamentally wrong with your headphones. There are a number of reasons you would get an output difference in one of the drivers. I'm equally skeptical of the "misshapen" diaphragm issue. A misshapen diaphragm would be fairly easy to detect, especially on a hand-made $700 RS1. You could have a dislocated voice coil or short-circuit in the wiring. Your driver could have been affected by a change in humidity or simply a wrinkle in the diaphragm causing it to produce the infamous "Grado grattle."
Whatever the case, if no one else will help you, I will. I'm finishing a project right now, but by the time your headphones got to Florida, I should be free for a new adventure. I've owned most of the Grado models - including the RS1 - and have experience taking them apart and reassembling them. If Grado doesn't help you out (a pretty big "if"), look me up and I'll do what I can for you - free of charge. All I ask is that you pay for shipping (both ways) and that you sing my praises when I'm done.
Maybe you could name your next kid, "Bilavideo."
