Ok, Robert sent me a new TFT clamp assembly. I'm guessing the Sofrider has a larger diameter TFT than the Conversion Kit, because...
I was originally going to replace just the cable stop, but found it wasn't easily removable from the lever on the TFT clamp assembly I received. On my original TFT clamp, the cable stop was just held in by friction and the tension from the front derailleur cable, I simply forgot to remove and save it when I removed the derailleur cable. So I decided to replace the entire TFT clamp assembly with the new one. Getting the two tubes separated was a bear, it didn't occur to me to grease the tubes when I originally assembled the TFT. I ended up squirting some penetrating oil in addition to main force to get them separated.
After cleaning off the oil, I wiped some bike grease on the inner tube, popped the TFT clamp on, pushing the tubes back together, hmm... shouldn't the clamp be somewhat snug over the outer tube? I tried tightening the TFT clamp as far as it would go and it still wasn't fitting. Pulled the tubes apart to get the clamp out and compared it to the original clamp. Definitely not the same size! After a few minutes, I realized I could unscrew the clamp quick release and remove the lever the cable stop is mounted on, so I swapped the lever/cable stop over to my old clamp and reassembled the TFT.
Spent an inordinate amount of time fiddling with the front derailleur, the derailleur cable, and the left brifter in 90 F/90% humidity weather but now I can shift my front again.