Remove drilled out venturi tube from base in thermador gas range?
OK, I did it. 

Here is how:

Remove the jet holder from the stove, put it in a vise (gently)

Insert spiral bolt extractor. Tap it in with two hammer taps.

Attach socket to end of bolt extractor. Use electric impact wrench, short bursts, and break it free.

Was able to remove three of four no problem. The fourth was frozen completely, and I will replace the whole thing.