WARNING: This page is about a different car, the 2015 Audi A7 Quattro, 2014 Audi A7 Quattro, 2013 Audi A7, and 2012 Audi A7. However, it is still accessible from the selected car via links, so may be relevant.
-- Check the torque converter hub -arrow- for wear grooves.
Fig 1: Checking Torque Converter
Courtesy of AUDI OF AMERICA, LLC
NOTE:
The torque converter must be replaced if it is damaged or faulty.