Thiel Customer Service - New ownership is terrible!!! - WHAT HAPPENED TO THIS COMPANY ?

There are two major points.

Firstly, I think old Thiel speakers keep to be
one of the best ones, in absolute terms. For instance, for my taste, Wilson Audio speakers, which cost is uncomparable to those of Thiel are no better - with apparently more defined mid and high ranges, they, for my taste, sound more sharp and bright. And lower frequencies of CS 6 and CS 7.2 and just incomparable with even largest Wilson speakers. 

So keep your CS 7.2 and keep trying to fix the tweeters. I have completed a similar task for my CS 6 about one year ago. Although it took almost one year, the coaxes were rebuilt successfully at Thiel. At that time, the telephone number did work and also e-mail communication was especially useful. Try to contact Rob  Gillum  at  rgillum@thielaudio.com. Although quite busy, he is a nice guy and I think will be able to repar your tweeter successfully, as he did with my two coaxes. Good luck!   

Very nice news, enjoy newly your CS 7.2s! 
According to my personal experience, Thiel speakers sound excellent with tube, as well as solid state amps. For instance, 50 watt Manley Stingray drives very well CS 3.6, I love the resultant transparent encouraging sound.  For 7.2s though you will need more tube power  I guess . You may also consider Manley monoblocks. And my McIntosh solid state 100 watts integrated amp combines also very well with CS 6, giving a soft, natural and detailed overall performance with clear deep bass. 

I did a similar job. Rob Gillum from Thiel said that it is ok to solder normally.
He even said not to use silver solder. Good luck