One way to solve this if you do not want to do it yourself is to contact a good audio shop in your area and see if they have a tech who can come over to your place.
When I had my adventures with the Thiel CS3.7, which also had a busted tweeter/mid issue like the KEF, I had the seller of the speaker pay for a tech from the local shop to do the fix (soldering). I found other issues and since I had seen how the tech did it, I went about repairing the other issues myself. The speaker sounded perfect after the multiple issues were resolved. I measured the speaker to confirm.
One thing that helped me was that the Thiel drivers did not need any calibration after installation. I had tweeter issues with my very old Ravel Salon 1 and Ravel asked me to ship the speakers back to them since they said they needed to be tested after a tweeter replacement. A real PIA since the tweeter failed 2 times.