I was at a tyre shop the other day and after a wheel alignment I had to get the steering wheel adjust to centre position.

I watched the mechanic lie on the floor with a spanner (or some tool) and do some sort of fiddling and he got up and it was adjusted. Looked easy. But I wasnt able to see what he did under there.

Can anyone tell me what he would have done and if there are any how-to instructions/videos on how to do this?

My car is a B8 A4 but I'm interested in the concept not going to play and break my own car :-)