If the midrange driver (the one directly below the tweeter) is indeed broken I would think you would have noticed quite a change as thats a pretty important part of the speaker! You might not be able to feel vibration on that driver like you will on the woofers because it doesnt produce as low of frequencies but if you put your ear up to it and it doesnt make any sound then I would give axiom a call and they will send you a replacement. If you really want to make sure its the driver itself and not the crossover you can take the midrange out of the other speaker and put it in the broken one to see if it works. I wouldnt reccomend repeated taking out and putting back the drivers though because the cabinet is MDF afterall and you can only screw into it so many times before its stripped out even when your careful.
