Suggested midrange fix for Thiel 2.2 speakers?

Can Thiel rebuild them for you?

Parts Express lists several Vifa speakers on their Website. (No affiliation).
Perhaps research other speakers that used that driver and try to find a parts pair
or advertise here in the wanted's section- someone may have a pair they're parting out....

Thanks for the suggestions!

If you could post high res close up shots of the front, back, side of the driver out of the cabinet, I could probably tell you which model you need to replace it.

Before Thiel starting making their own drivers, they used off the shelf drivers. But.. many of those "off the the shelf" drivers were modified to Jim Thiels specifications. Just using off the shelf driver replacements may cause a mismatch between channels, and/or effect the time and phase response with the cross-overs that were designed around those specific drivers.
If Thiel can't or won't rebuild it (and I really doubt that) perhaps you should try Miller Sound in Philadelphia. If you decide to use someone other than Thiel; I'd suggest sending the matching driver from the other speaker for comparison sake.

http://www.thielaudio.com/
http://www.millersound.net