WARNING: This page is about a different car, the 2010 Audi A4 and 2009 Audi A4. 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 Converter Hub For Wear Grooves
Courtesy of AUDI OF AMERICA, LLC
NOTE:
The torque converter must be replaced if it is damaged or faulty.