Rick, you've got it - 1" is the total back-and-forth play (as per MB spec for a 124). Rotation beyond 1/2" in either direction from center should begin to move your tires.

As you've gathered from these posts, there are many linkages along the way that can account for any additional slippage.

Also be alert to design-differences between models before transferring the helpful recommendations and experiences of others (when the weather gets better!)

Regards, Barrie