I had a pair of BP2006s several years ago that I bought new that developed a rattle while I still owned them.
I removed the plate on the back of the speakers and found were positioned very close to a hard surface and once the the speakers begain working would bounce the capacitors against something hard causing the rattle. All I had to do was to move them a little.....using something that was insulated. Try not to fry yourself if you snooping in there.
I probably don't have to tell you this but the guys over at Def Tech are great to work with.
Samsung 64F8500, Panasonic 65VT50, Oppo 95, Tivo Roamio for OTA, Dish VIP722, Marantz AV8801 preamp, Rotel Amps, Atlantic Tech 8200 speakers, Seaton Submersive HP, Calman 5, Chromapure, VideoForge HDMI II, i1Display3pro, i1pro2, eecolor colorbox.