That coaxial driver will be unique to them for sure, they are likely the only source for it, regardless of who built it for them (or they built it in house). "Not fully blown" sounds to me like a damaged voice coil - it will work a low power and certain frequencies, but when you turn it up, it will distort.
It is a 4 Ohm speaker as well, dipping to 3.4, and with a low sensitivity, that can be an oddly tough speaker to drive.