I claim no more knowledge than that which Google has blessed me with, but
this link to ebay has at least a picture for everyone. You could even buy them from the US I guess.
Other than that, it seems you are right about the JBL connection and if you search for JBL 375 you get the same item.
So, perhaps you could contact JBL? I'd suggest calling them though. You need to get through to someone who 'really' knows what they're talking about.
My contacts list is well out of date, so hopefully someone else can suggest a good point of contact for you.
If all that fails then you could always re-wire and use some Maplin piezos......