Since you heard the "healthy" speaker being noticeably stressed during those heavy bass scenes and the only problems with the suspect speaker was with those particular scenes, you easily could have blown or had a defective woofer that shows up during that content. You also noted the noise followed with a particular driver. For now, it is probably best to wait for the replacement driver, swap it in and see if it fixes your issue. If it doesn't then looking at the crossover and other variables would be a good idea. I know it will take some patience but try to eliminate one variable at a time.
Good luck.
